Move and "privatize" internal functions
Add test for percent function
Add percent function
Add doc for percent function
Add internal strip-units function
Add tests for em and rem functions
Better parameters name for percent function
Fix tests
Add test cases for em with no base value
Add em function
Add rem function
Remove em-base global variable
Add docs for em & rem
Add tests cases for placeholder
Add placeholder mixin
Add doc for placeholder mixin
Add a verification to placeholder mixin