Stop lvalue check from segfaulting when coming across buggy IL code (IL operator with no operand!)

Allow get_datatype_info_c to be called with NULL parameters.

Do lvalue check of function output parameters (since they may contain expressions inside array subscripts!)

Handle buggy source code gracefully (do not bork when non-array variable is used as an array. e.g: int_var[42]:= 33)

Delete debugging messages left in by mistake.

Fix segfault when doing lvalue check of buggy IEC 61131-3 source code

Fix datatype analysis of structured variables that contain arrays in their fields (e.g. var.x1[var2 + 42].y1).

Add capability of returning array subscript list while decomposing a struct/array variable.

Code cleanup: Remove unused option = Delete dead code.

merge

Declare that YYLSTYPE is not the default trivial datatype used by bison. (was causing compile errors in bison ver >= 2.7)

Fix build on Ubuntu 13.10

Fixed warning when compiling generated program containing external variable assignments

Enlarged flex buffer size in order to accept larger C pragmas

Missing braces arround extern declarartions in __SET_EXTERNAL define was making problem with GCC in switch case statements

Moved __INIT_* defines within type definition headers files

Fixed warning in accessor __SET_EXTERNAL

Fixed bug when defining task with single_data_source instead of interval_data_source

Merged Mario's changes

Fix bug related to FB invocation of FB instances declared as VAR_EXTERN.

Merged Mario's changes

Partial fix to VAR_EXTERN vs VAR_GLOBAL check. Now considers globals declared in resources too. TODO: recursively check FB declared in the program.

Allow variables declared inside resources to be referenced by res_name.var_name

Add a new node to the abstract symtax tree, which will let us do datatype checking of FB variable declarations using the standard algorithm, and no special cases.