Adding semantic analysis

• Add script "run" to make it easier to test the compiler
• Add negate unary operator to EPLan
• Update documentation
• Ignore .iml files
• Rename the generated parser class
• Add location to AST
• Add unit name to lexer
• Add simple GUI
• Add more command line options
• Add type package and type representation for 'real'
• Add type mismatch error message
• Only generate code in the absense of errors
• Add semantic analysis
• Rename class 'ExpNum' to 'ExpReal'
• More flexible generation code to print the result