Remove doc from API.txt
    
    Doc parts are not removed from the API completely. This leads to
    unnecessary updates to API.txt when the option/argument documentation
    is changed.
    
    This patch replaces unreliable doc stripping function with a regular
    expression. It works for all current doc strings (simple string or
    GetText). The only limitation is that the RE supports only up to
    2 levels of nested parentheses in doc string.
    
    https://fedorahosted.org/freeipa/ticket/1057