Modified the pratt parser so that the parser can accept any nud and led function
Provide a test for parser, to verify the usablility of the codes.
Created nud() and led() that handle for infix expression.
Save the system files that created by pyCharm compiler.
Added a function in context to handle the special case for + and - : can be prefix or infix
Added a new test for prefix operator and change the addOperator to the correct function for the previous test.
Completed the postfix nud and led.
Completed the parsing for expression inside the { and }
Fixed some small test part.
Imported nud and led for ( and ) from Bing Xuan code.
Added one more test for the { and } brace to identify multiple statement inside.
Completed the nud to identify if and if/else for simple expression.
Merged both source code from Bing Xuan.
Changed some small bug inside.
Modified test , so that it match the system.
Merged with the latest.
Merge pull request #4 from jwchong93/master

I merged with the latest