Update year to 2014 in generated files
Add copyright and auto-generation notice to built-in sources
Move built-ins generators from 'runtime' to 'builtins'
Refactor built-ins source generators
Add GenerateBuiltInsTest

Tests that generated sources of built-ins (Functions, Ranges, etc.) are
up-to-date
Remove outdated hack in DeclarationResolver
Fix variance in Progression and Range
Delete outdated hack in Unit