Add tool to read index maps from text files

[dladams]

We would like to be able to read data from channel maps such as vdcbce_chanmap_v4.txt) into index map tools.
In particular dataprep issue 28 needs a map of FEMB IDs for offline channel IDs, the first and tenth fields in the preceding file.

[dladams]

I created tool TextIndexMapTool that does the above.

While doing that I found and fixed a bug in StringManipulator::split. It was not splitting on the the second and later separator chars provided in the first argument.

Pushed mods after test passed. Had to update to v09_72_01d00 to push.