Add check bison version in configure.ac file.
To build correctly matiec we need bison greater or equals than 2.4 version.
Now the "configure" script is able to check if system has correctly requirements.

Remove remaining signed/unsigned comparison error messages when compiling.

Remove warning about comparisons between int and unsigned int.

Support for data types of STEP.T and STEP.X in SFCs

Remove dead code.

Change code formatting (alignment)

Aloow use of SFC STEPs as variables.

Check lvalues in expressions passed to Function/FB IN parameters.

Fix comment (bug found by Manuele).

Remove warning about redefining "__STDC_LIMIT_MACROS" (bug found by Manuele).

Constant folding for IL.

update comments.

fix bug: remove REAL from candidate datatypes when real constant has overflowed.

signed integer limits do not affect ANY_INT constant values.

comment out un-used code.

cleaning up code. Changing HUGE_VAL to INFINITY.

Cleaning up the code.

Clean up the code a little.

Fixing includes to define INTxx_MAX etc...

Add remove_from_candidate_datatype_list method using constant_folding results.

fix typo.

fix parsing of non base 10 constant values.

determine const value of hex, octal and bin literals correctly.

fix array bounds check.

Fix stupid typos (in calculating array dimension)!

Add file missing from previous commit.

Add ERROR_MSG macro && move extract_XXX() functions to constant_folding.cc

Add independent extract_integer() function (preparing to remove extract_XXX() from absyntax_utils.cc)

Clean up code (remove parsing of integers in stage 4).

Fix literal MACRO gcc compliant.

Add 'dimension' parameter to subrange_c, fill it correctly, and use it.

extract_int64() must not handle negation operation (was doing it incorrectly for INT64_MIN!)

Add support for -INT64_MIN values in literals.

Make compiler portable (do not assume int64_t is long long int)

Add missing set overflow flag.

Fix extract_integer_value.
Now we handle signed and unsigned in different mode.
(Thanks to Andreas)

Fix typo (thanks Manuele)

Remove potential access to NULL pointer.

fix error message.

Fix array index bound check to consider uint64 indexes/limits.

Fix structure initialize.

Add check array out of bound.

Code for debugging const_value annotations in abstract syntax tree.

Fix 'overflow' detection for real64.

small bug fix.

Fix compare expression in constat folding class.

Fix extract_real (thanks Manuele), and add check for overflow.

cleaning up the code...

Fix remaining overflow checks.

remove incorrect include file.

Correctly implement MOD operation and overflow checks (still missing uint * / MOD).

Re-insert errno=0 before calling strtoXX() (thanks go to Manuele)

cosmetic changes.

Add data structure for storing overflow of constant values.

make the compiler platform independent (i.e. no longer assume sizeof(double)==8).

create extract_real_value() in absyntax_utils. NOTE: overflows not yet handled!

Update constant folding: fixing minor bug.

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 ..