Change some conditionals involving string literals to use strcmp instead.

The current usage throws some compiler warnings.
Changed a line using TrdHCalibR to use a static function.
Corrected grammar of a function name.
Added dedicated threshold variable along with getter and setter
functions
Added corridor_radius variable along with getter and setter functions.
Added default values for threshold and corridor_radius to Init_Base.
Removed threshold parameters from various functions.
Removed MinimumDistance, and setter function.
Added variable containing total number of tubes to TrdHCalibR
Added reserve statement to Construct_TRDTube
Added variables to store the corridor position and direction and
created getter and setter functions.
Added preselected variable to track whether the preselection has been
performed.
Added function to tell whether a hit is good or bad.
Added vector of corridor hits.
Added function to fill the corridor hits vector
Added function to Fill the whole TRDHitCollection
Removed the RemoveDuplicates and the AddEmpty tubes functions
For the forloops which need it, I changed them to use the corridor hits
vector.
Made OffTrackHits take only those hits above threshold.
Added functions for OnTrack hits.
Added GetNearTubes functions
Added SetCorridorHits into SetThreshold.
Added functions to fetch size and hits from the corridor.
Changed TrdSCalib to reflect the TrdKModifications
Use the TrdHCalibR variable giving the total number of tubes
Fix conditions defining the corridor
Make some getter functions const
Added some set corridor overloads. This allows you to set multiple
properties of the corridor without having to find a new corridor with
each new property you set.
Removed threshold from the calculation of a corridor. Changed the
corridor setter functions to reflect this.