Global variable type evolved: added missing optionnal attributes.
Added missing keywords to lexer/parser.
Added thread_local_storage type.
Splitted global / function definition attributes rules in parser.
Added dll_storage rule to parser.
df_attr rule splitted into df_{pre,post}_attr rules in order to avoid conflicts
with return type parameter attributes.
Added comment about parser conflict.
Implemented fast-math flags.
Implemented volatile flag for load and store operations.
Implemented NSW / NUW / EXACT flags.
Removed unused dll rule (duplicate of dll_storage rule).
Merge branch 'master' into test
Removed attribbute group from TODO list since it has been implemented.
Merge branch 'master' into test