renamed fieldmapy -> fieldmap
split out example for fieldmap, added map files for testing
some minor  modifications of the functions

added files: fieldmapy.py: has several functions which are useful for manipulating the data for TraceWin fieldmaps
                   SP_Relativity: has several function which return relativistic beta and gamma from energy and vice versa
		    TTF.py: has few functions for calculating TTF of cavity fieldmaps
added example: Scan_Energy_gain_in_fieldmap-v16.pynb which has several functions and examples for phase scan (to be completed)