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 [] <search_id>
class anymore <search_id>
class donesearch <search_id>

[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: 5330698 thanks to @jamespic

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

still missing