Add conditional event script execution

[smartin015]

This closes out #104 by adding in optional conditional scripting to prevent an event-fired script from executing.

• Add print file metadata to AST symbol table when evaluating conditions
• Finish integration tests
• Update settings UI to properly display conditional state
• Update docs to describe how to set up conditional scripting, plus what values are provided in the AST's symbol table
• Experimental testing
• Fix "load from profile" icon