[Templates] New text.replace virtual method for v2.15

[Sergey Martynoff]

> I'm attaching a new test file you can run along with a file of 
> benchmarks.

It was a good idea to benchmark the sub. At least it is obvious
now, that replacement without backreferences should be handles
separately, the simplest way. I ran the benchmark on my windows
pc, and get similar (even more contrast) results.

Totals:
                                      Rate      replace_andy
replace_andy                  13224/s           --
replace_andy_with_patch 20224/s          53%
replace_josh_new2          27434/s         107%


I don't think using no strict 'refs' is a big trouble (at least it
is used quite often in so many modules), so IMO josh_new2 may be a
good candidate.


-- 
Sergey Martynoff