Settings: Load global settings on launch

Fixes #362

This used to be called from the constructor in
an unused static field; I can't find which commit
that was deleted in.
Compiler: Improve variable / parameter names

Also make sure that the error
output file is always deleted
Compiler: Refactor compiler args

Don't use per-compilation instance state.
Use StringBuilder to avoid duplication.
Code: Fixed JsonProperty support

Use correct attribute property name
Unify attribute name code
Merge pull request #366 from SLaks/misc-fixes

Misc fixes