Release 1.2.0

• Fixed a few edge cases involving Windows line endings, all code is now converted to Unix line endings before processing
• Added a new variables section under build targets, for providing variables used inside the build process
• Added a new --var: build flag, for setting the value of variables from the command-line, example: --var:debug=true
• Added new ---@if, ---@else and ---@end compiler directives
• Added support for building only a single build target from the command-line, example: du-lua build production