Fix a few bugs of previous commit.

Start constant_folding class.

little typo in last commited code
add if(is_bool_type(sym)) this->bool_type->accept(*this) in generate_c_il_c::visit(il_default_variable_c*)
to get .BOOLvar instead of .FALSEvar resp. .TRUEvar ..

Change return data type of array_dimension_iterator_c.next()

Fix SFC stage4 error.

Renamed class, remove unused code, delete allocated objects.

Start sematinc range check class.

Located variables may have other data types besides ANY_BIT.

Add verify_is_lvalue to control_variable in for_statement.

Remove useless code, and replace with assertion.

Fix bug: initialise un-initialised variable.

Delete incorrect comment.

Add some comments...

Add high level comments.

Fix comment.

Fix the previous commit: check for errors in expressions used as subscripts.

Fix data type check array subscript field.

Merge changes.

Fix parsing os TIME literals & rename the extract_integer() function.

Fix generation of output for iec2iec.

Do not compile deleted files...

Do not compile deleted files...

ReDelete files - used in old method of supporting standard functions.

Remove file (used for old method of supporting standard functions).

Add TODO list!

Delete unecessary variable.

Fix __dt_to_timespec primitive function.
Set tm_isdst = 0 to disable DayLight Savig Time.

Fix __dt_to_string primitive function.

Fix code generation about __INIT_GLOBAL_LOCATED.

Change constants into enums.

Add lvalue checking for IL function and FB invocations.

Fix comment.

Add clarifying comment.

Remove access to NULL pointer.

Make temporary fix to is_complex() method.

Fix comment. (thanks go to Manuele for pointing it put).

Stop lvalue checks after finding an error in the expression.

Remove erroneous check for S1 and R1, and add missing declrataion.

Start implement lvalue check in IL instruction.

Add lvalue check on fb invocation.

Literals are also part of expressions!

Implement check_assignment_to_expression in lvalue_check_c class.

Remove potential access to NULL pointer.

Start having nicer stage 4 error messages.

Improve usability command line under windows.

Ignore trailing EOLs when determining symbol location.
(Makes for niver error messages)

Add comment.

Fix Segmentation fault in check_assignment_to_output lvalue method.

Remove deprecated status for ANYTIME operations.

Produce similar error messages in stage2 and stage3.

Fix bug when handling code with data type errors.

Fix printing of data type errors in while and repeat statements.

Add lvalue check for non formal function invocations.

Fixing check for assingment to FOR control variables.

Moving get_var_name_c into its own file.

Fixing check for assignment to output variables.