Shms dc calib (#140)

* added option to read input file and event number to loop over

* added option to read input file and number of entries to analyze

* swapped x:y axes in 2d plots to display drift times vs. wire number, and added labels to the axes

* minor change in output file name

* added option to read filename, and changed the naming scheme of the output .root and .dat files produced

* added option to read input file and number of events, also changed naming of input and output .dat files to be consistent with the other changes made so far.

* added option to read input file and number of entries

* added option to read input file and number of events, and also added axes titles to histos

* added option to read input file and numberof events, also modified name of .root file being read

* added axes titles to histos

* added option to promt user to enter input file, run number, and number events to analyze. Also made a few improvements overall