Support for semantic verification of calls to standard functions.
This commit makes a fundamental change in the way standard functions are handled by the compiler.

Fixing exponentiation used with symbol **

Fix bugs in exponentiation

Fix case statement in ST, adding support for enumerated types

Adding BYTE operators visit functions in inlinefcall

Fix bug with DIV and MOD operator in IL code generator

Fix bug in suffix of inlinefcall call in ST and IL

Remove inclusion of missing file in lib

Commiting merge with Mario's repository

commiting merge with Laurent's repository

changing 'make' to '$(MAKE)' so other make tools (e.g. gmake) may also be used.

Replacing extern declaration with #include of apropriate header file

Adding some comments, and removing a check for a semantic error in code being compiled.

Fix bug with inline function call in POU programmed in IL

Fix bug in function calls with literal parameters

Fix makefiles when not using make as make tool

Fix bug on initialization of temp variables not using setter

Fix bug when trying to find the type of a NULL symbol

Fix bug in inline function calls when using function with undetermined type interface with literals as input

Fix warnings when compiling matiec

Fix warning on nop statement at the end of function_block and program generated code

Adding double underscore in computed enumerated value to avoid conflict with other user defined identifiers

Add support for finding type of a constant enumerated value and managing conflict between same identifiers defined in different enumerated data types

Fix bug in declaring variable of enumerated type