Allow hand-alignment with spaces when using tabs to indent

[bendmorris]

Currently, either tabs or spaces must be used to indent, not both. It's common to use spaces after indenting for alignment purposes, for example:

https://github.com/HaxePunk/HaxePunk/blob/0cc6d89b58f9c13ee1eecd9bff8aea78b1d9fd56/com/haxepunk/Preloader.hx#L22

Could add an option to pass lines which begin with tabs and don't include any tabs after spaces (i.e. don't mix tab-space-tab.)