Add support for non standard feature: allow POUs with no in, out and inout parameters

Add option to not add the EN and ENO parameters to every function and FB (generated C code becomes smaller, and uses less memory for function invocations)

Correctly identify errors when parsing erroneous code (make sure flex goes back to INITIAL state when code contains errors that do not allow determining whether ST or IL is being parsed)

Created new branch fix_compilation_warnings

fix compilation error about missing braces

IEC_TIMESPEC has two fields tv_sec and tv_nsec.

Compilation error:
./build/POUS.c:600:45: error: missing braces around initializer [-Werror=missing-braces]
static const STEP temp_step = {{0, 0}, 0, {0, 0}};
^
compilation terminated due to -Wfatal-errors.

fix warning about overflow if matiec is running on 64-bit platform,
but the generated C code will cross-compiled for 32-bit platform

For example:
./build/config.c:29:39: error: large integer implicitly truncated to unsigned type [-Werror=overflow]
unsigned long greatest_tick_count__ = 18446744073709551611UL; /*tick*/
^
compilation terminated due to -Wfatal-errors.
cc1: all warnings being treated as errors

fix C compilation warning about function prototype in __SET_EXTERNAL

Example warning:
./POUS.c:1220:3: error: function declaration isn't a prototype [-Werror=strict-prototypes]
__SET_EXTERNAL(data__->,KN_AUT,,__GET_VAR(data__->KEY_AUT.STATE_OUT));
^
compilation terminated due to -Wfatal-errors.
cc1: all warnings being treated as errors

fix C compilation warning from gcc about /* inside of comment section.


./beremiz/iec_std_lib.h:240:1: error: "/*" within comment [-Werror=comment]
/*
^
compilation terminated due to -Wfatal-errors.
cc1: all warnings being treated as errors

Update README.build file with instructions for crosscompiling to win32

Delete commented out code.

Fix FB calls in IL (FB variable name was showing up extraneously before the C function that initializes the POU containing the FB call)

Delete unused code.

Add check for repeated elements in a CASE statement. Emit warnings (and not errors) if found.

transform CASE into if()..else if().. -> fixes 2 bugs (1)case within case statements, and (2)repeated elements in case options

Initialise arrays to their correct default values - Fix bug introduced in commit 477393b00f95 (2014-11-16)

Fixed reset of current_varqualifier when generating global initializers, causin RETAIN and other option to be ORed and applied to all subsequent global variables.

Do fill/narrow datatype analysis algorithm for derived_datatype_identifier_c (fixes bug related to arrays of arrays that was generating incorrect C code).

Better identification of error location in some error messages.

Fix bug introduced in 2014/10/19, while adding support for REF() opertors -> datatype checking was not catching datatype inconsistency errors!

merge

Re-write and fix the logic of SFC action modifiers.

Correct the number given to actions in the #define's

Do not allow constant_propagation algorithm go into infinite loop when analysing code with circular references.

Do constant propagation of FBs instantiated in other FB or Programs, so that variable sized arrays can be declared in FBs too.

Do constant propagation of instantiated FBs, so that variable sized arrays can be declared in FBs too.

Let get_datatype_info_c handle variable sized arrays, even if constant folding is not yet done.

Correctly analyse external<->global var compatibility when using variable sized arrays (TODO: does not yet work for FBs!)

Add comment about bug that needs to be fixed later on.

Break constant_folding_c in two classes: constant_folding_c and constant_propagation_c

Add check whether the same constant var_external variable is initialised with two (or more) different constant values.

Change algorithm for propagating VAR_GLOBAL constant values to corresponding VAR_EXTERNAL.

Disable constant propagation again (still not working correctly)

Make support for use of variables in array size declarations a command line option (off by default)

Add debug_c::print(const_value_c) for printing of const values.

Add is_undefined() method to const_value_c

Make error message more informative.

Add comments.

Add checks for use of non constant value in subranges, and lower_limit > upper_limit.

Fix previous commit (symtable operator[] must return a reference to the stored value!)

Do constant propagation of configuration/resource variables, taking into account scope of variables.

Change dsymbtable_c -> use design pattern used by C++ standard library (STL)

Change symbtable_c -> use design pattern used by C++ standard library (STL)

Remove debugging code left in by mistake.

Do constant propagation inside Configurations and Resources (required for support of extension: array [1..max] OF int); (Resources is still buggy)

Do constant folding of default initial values of datatypes.

Do constant propagation to symbolic_variables, and correctly handle constant folding and propagation of variable declarations.

When generating C code, use the const_value of a symbolic_variable when it is used in a subrange.

Small code re-organization of how const values are stored in symbol_c (can now be accessed through member functions, instead of macros)

Fix bugs introduced in previous commit (once again do constant folding of all literals in type declarations)

Do constant folding of variable's initial value (allows correct C code generation with variables in the subrange of an array declaration: ARRAY [1..max] of INT).

Delete un-used declaration.

merge

Allow variables to be used when declaring the dimension of an array.

Fix C code generation when forward references (-p command line option) is on.

Add a new pou_typename_c object to the AST to store references to previously declared Functions, FB, and Programs.

Delete unused file.

Make use of pre-parser a command line option.

Fix AST generated by parsing with preparsing switched OFF (typo in array datatypes, and fix parsing of POUs).

Fix AST generated by parsing with preparsing switched on, and allow parsing to work with preparsing off.

Fix bug introduced when adding support for relaxed datatype model: change derived_datatype_identifier_c to identifier_c when used as an identifier