new api to return custom subclasses of String and optionally set @html_safe=true
Move html_string_class into a global

This is so we can perform some checks on the value passed in ahead
of time
bring global getters up into ruby
no need to cache IDs for global setters
run assignments in C at load time
always set @html_safe=true
fallback for rbx, etc
oops
avoid unnecessary rb_str_dup in the rbx case
use new escape_html_as_html_safe for html_safety module
fix html safe test helper
just use an ivar
html_string_class -> html_safe_string_class
revert to old html safety behavior
fix rbx1.9 maybe
Revert "fix rbx1.9 maybe"

This reverts commit cee7ac952d0996bab4629101e8c78412c89429c5.
rb_cEncoding is already defined
Merge pull request #30 from brianmario/as_html_safe

EscapeUtils.escape_html_as_html_safe