[Users] Piraha in the Flesh

[Steven R. Brandt]

I've hacked a version of Cactus to use Piraha for parameter parsing. 
Please take a look:

https://svn.cactuscode.org/flesh/branches/with_piraha

This version is able to run the ET testsuite.

This version can understand the variables $parfile, $ENV{name}, and $pi 
(which is 3.14...). Variables can be standalone, or be substituted from 
inside strings.

It can understand mathematical expressions including grouping, order of 
operation, and a few functions (sin, cos, tan, exp, sqrt). Other 
parameters from the parameter file are available for use in mathematical 
expressions.

Some debug printing is in place so you can get an idea of what's going on.

Cheers,
Steve