datagroup functionality support (with class command)

[samstep]

I would to request the data group functionality in TestTcl, which I belive shold cover the following:

1. ability to declare the datagroup and its contents in "it" or "before" in the test file
2. support for "class" commands in iRules e.g:

class match [] class search [] class lookup class element [] class type class exists class size class names [-nocase] [] class get [-nocase] [] class startsearch class nextelement [] class anymore class donesearch

[landro]

This should be relatively easy to implement. It could be implemented in a way similar to the TesTcl event command for expectations.

[landro]

Partially closed by SHA: 5330698378a2d1ddff0d2b00876a0321a61b00c1 thanks to @jamespic

type -
names -
get -
startsearch -
nextelement - 
anymore -
donesearch

still missing