User Experience Improvements

• Added support to the VSCode and Sublime Text language extensions for editor hovers for mnemonics, labels, and constants; plus improved semantic syntax highlighting that differentiations label and constant definition from label and constant usage.
• Updated the #include preprocessor directive to allow relative paths in the specified included file. The relative paths are resolved relative to the file currently being compiled.
• Fixed bug where conditional compilation was not handling constant definition correctly.
• Added user warnings for scenarios that wouldn't prevent a successful compilation but are potentionally an unintended bug by the user. Warnings can be elevated to errors with the -W command line option.
• Consolidated all error, warning, and info handling into a centralized manager class. This will allow more consistent behavior in the future.