Fix bug in Lua parser for function declaration with varargs
Add Lua parser test for function with variable arguments
Fix the AST generation for string concatenation operator
Fix problem in Lua parser for single argument function call
Improve error message from parser in case of end of file
Rationalize and cleanup files for Lua parser

Remove some unused files and rename the bytecode generator module to
"generator" to avoid confusion with the bytecode module itself.
Fix parser testing script to adjust the command line arguments