initial naive stencil implementation

The current stencils are limited: only up to 2 dimensions are
supported, all dimensions must be of the same size.
implement symbols
implement the symbol table
initial lex/yacc implementation
ignore lex and yacc generated *.[ch] files
update Fedora requirements

The previous instructions for Fedora told to install the flex/bison
programms but failed to advise to install the associated libraries as
well.
Merge branch 'llama' into dev

The current syntax seems to cover all basic cases.
Merge branch 'internals' into dev

The symbol table should be ready for use.
fix symbol_table_get()

The previous implementation initialized an internal variable to -2
instead of -1. The function would not do what it was supposed to do.
This resulted in the function not finding symbols when they exist, and
returning -2 in all cases (no matter whether the symbol exists or does
not exist).
update Makefile for internal structures

The new Makefile now compiles the currently existing internal structures
needed for the syntax analysis. A new variable (PROGRAM_OBJECTS) was
also introduced to facilitate the addition of new targets.
remove const qualification of symbol_table_get()

The const qualification of this function was not necessary and would
make things harder.
Merge branch 'dev' into symbols
add symbol_table_get_from_index()
first symbol saving implementation

The current implementation supports the declaration and the definition
of integers. Stencils are partially supported. Arrays and function
identifiers are not yet saved.
Merge branch 'symbols' into dev

The symbol table stores most identifiers.
implement quads
implement quad lists
add utilities for yacc

- New quad_value constants were created.
- New quad for returns that return an operand.
- New quad creation functions for the most used branchs:
  branchs on equal to 0 or 1
initial quad use in lex and yacc
fix unduplicated identifier