Create firings.mda file from MClust .t files

[mvdm]

Needed to be able to compare MountainSort output to manual sorting.

This function will need to do a few things:

• Iterate over tetrodes (1:nMaxTetrodes)
• Find which .t files come from this tetrode
• Iterate over .t files for current tetrode
• For each spike, find index of accompanying 32k CSC file (generated by NTTtoNCS.m -- it is critical that these match!)
• For each tetrode, write .mda file containing idxs with matching cluster IDs
• Can probably ignore first row (containing ID of wire with max peak) for now
  (see output format description here)