Start using /static/images

4.2 removed the images autohandler, so things served from an extension's
NoAuth/images/ now go through mason and come out broken.

Unlike static/js and static/css which "just work" because of
RT->AddJavaScript and RT->AddStyleSheets we test for $RT::StaticPath
which only exists when we have /static/ and manually frob the paths.
Newer MIRTx for /static/ support
Pull in newer lib/ prose that pulls down into README
Bump version to 0.13 and update/tidy Changes