Added Guard Asserts to all public Lexer.c interfaces.

Signed-off-by: Christian Gunderman <christian@sonofboss.cwru.edu>
Added type output to lexer_next and lexer_current_token
	Also performed some minor work on the compiler.

Signed-off-by: Christian Gunderman <christian@sonofboss.cwru.edu>
Updated Lexer to handle logiparenth ( ) { } [ ] as single character operators, disallowing their usage in multicharacter operators.
Drafted func_defs_parse_args() function in compiler
	Compiler now successfully recognises function declarations.

Signed-off-by: Christian Gunderman <christian@sonofboss.cwru.edu>