Implemented Lexer, Parser and AST module.
The grammar seperates the automake rule into left side and right side. It
divides the left side according to the primaries like PROGRAMS, LIBRARIES.
* Lexer.pm: Lexer module. Converts a string into tokens.
* ParserTable.pm: Contains the parsing table.
* automake.y: Contains the grammar.
* automake.png: Contains the state transition diagram generated by the
grammar.
* Tree.pm: Contains submodules for creating tree nodes.
* parser.pl: Implements the parser.