Rename some core::option functions

from_maybe => get_with_default
maybe => with_option
may => with_option_do

I know these names are kind of ridiculous, but it's the best I could think of.
Feel free to bikeshed. Closes #2081

src/librustsyntax/parse/eval.rs

@@ -23,7 +23,7 @@ fn eval_crate_directives_to_mod(cx: ctx, cdirs: [@ast::crate_directive],
     -> (ast::_mod, [ast::attribute]) {
     #debug("eval crate prefix: %s", prefix);
     #debug("eval crate suffix: %s",
-           option::from_maybe(suffix, "none"));
+           option::get_or_default(suffix, "none"));
     let (cview_items, citems, cattrs)
         = parse_companion_mod(cx, prefix, suffix);
     let mut view_items: [@ast::view_item] = [];