Added support for Conditional statement and Test files.

Added support for Conditional statement and Test files.

* automake.y : Updated to handle conditional statement and empty variable
* defination
* parser.pl : Updated to read from standard input and write to standard
* output. In debug mode, output on standard error stream.
* Converter.pl : Updated to handle empty grammar definitions.
* Tree.pm : Updated to handle conditional statements and write output to
* standard output
* Makefile : Added action test.
* test.sh : Read all text files in t directory and generates corresponding
* standard output
* Makefile : Added action test.
* t/*.txt : test files.