Start to change code like Mario suggestions.

Create functionDataType array in derived_conversion_functions_c.

Add conversion functions option.

Start enumerate conversion functions.

merge

Be sure to not redefine TRUE and FALSE macros.

merge

Removed unused __attribute__((__packed__)) only gcc compatible.

Protect IEC_STD_LIB.H header agaist multi-include problems.

merge

Start to move enumeration declaration checking to its own class.

Fix comments and code alignment

Fix warnings previous change introduced when compiling with gcc.

Fix some important clang++ warnings.

Allow use of type#value syntax when defining default initial value inside a TYPE..END_TYPE declaration.

Do datatype verification of fully qualified enumerated values (e.g. ENUMTYPE#enumconst)

Add datatype checking of enumeration data type declarations.

Print const values of symbol.

Fix code generation of enum value constants (this is a temporary fix - it will be followed by a code cleanup).

Fix bug in datatype checking of enumerated datatypes delcarations.

Fix datatype checking of enumerated datatype declarations. We now follow the fill->narrow algorithm correctly.

Add method to determine the id (name) of a datatype.

Change the base datatype of enumerations to an enumerated_type_declaration_c (for named types!)

Change the public interface to debug functions.

Check for errors in enum datatype declarations. (This is not yet complete as it will not yet stop the compilation process if these errors are found)

Fix one more bug - upper_bound() works a little differently to what we want!

Fix more bugs in dsymtable_c (real semantics of std::multimap::lower_bound is not what was assumed!)

Fix counting bug in dsymbtable_c

Use duplicate symtable instead of symtable for enum constant value table (this will later allow us to detect semantic errors in IEC 61131-3 source code)

Move the enumerated_value_symtable to fill_candidate_datatypes_c, since it is only used there!