Fixing some bugs in lvalue checking (other bugs remain - to be fixed later)

Add lvalue check class.

Determine the modifiers (CONST, REATAIN) used when declaring a variable.

Fix typo in comparison expression.

Removing code from search_varfb_instance_type_c (use search_var_instance_decl_c instead).
(Preparing to delete search_varfb_instance_type_c in the future!)

Fix bug by expanding permissible data input of search_var_instance_decl_c
(this will also prepare us for removing search_varfb_instance_type_c in the future)

Edit formating and delete unused code.

Start data type checking of var declarations (including direct variables!)

Delete incorrect comments I had inserted previously (confusing EQ and NE functions)

merging with Lauren't changeset.

merge with Laurent's changeset (essentially ignore all changes).

merge with Laurent's changeset (essentially, ignore all changes).

merging with Laurent's changes.

merging with Laurent's change.

merging with Laurent's revision 55b074ea7255 (essentially ignoring all changes)

Add coment warning about incorrect implementation of the NE standard function.

merging with Laurent's patch.

Print correct error message when handling IL function calls.

Edit error message.

Add EXPT widen table.

Some stupid code cleanups.

Some code cleanups.

Clean up the code.

Fix error messages of il function calls - it now prints out location info of first parameter.

Clean code for printing errors in expressions.

Clean code for comparison operations & operators.

Cleaning up XORN, ANDN, and ORN operator code.

Cleaning up some code.

Add 'widen' tables for AND, OR and XOR operations.

Add MOD widening table, and some code clean-ups.