[htmltmpl] default_escape patches

[Tom H. <tom...@pu...>]

Attached are patches/tests for the following bugs:

* when specifying a default_escape, you can't turn it off

I have fixed ESCAPE=0 and added ESCAPE=NONE to turn off escaping 
altogether for a TMPL_VAR.  The pod was also updated to reflect this change.

Usage:
  <TMPL_VAR foo ESCAPE=NONE>
  <TMPL_VAR foo ESCAPE=0>

* ESCAPE='JS' did not work

I fixed a regex so that single quotes around JS now works.

I have also added a new test file: 04default_escape.t

Tom