move 'yarpros type' to 'yarpidl_rosmsg', make it work like 'yarpidl_thrift'

The thrift IDL code in YARP is better organized and has better macro support than the older, neglected ROS msg code. This commit refactors functionality from `yarpros type` to make it work analogously to `yarpidl_thrift`, and established a framework for tests. Once this is in place, work on issues #24 and #26 will be easier to do in a solid way. This commit fixes issue #19 along the way.

With this change, parts of tutorials such as http://wiki.icub.org/yarpdoc/thrift_tutorial_simple.html can be reused/generalized for ROS's IDL.