Changes
- Ensured consistency by ending every line with a semicolon
- Added two MathML file-extensions (*.mml and *.mathml;) to "XML="

Justification for proposed changes
- Code consistency is important in programming
- MathML is a form of XML that is commonly used and is part of the HTML5 standard
- W3 MathML Specification: http://www.w3.org/TR/MathML3/
- Geany properly highlights the code when the MathML file-extension is recognized