Further additions

[Mellechowicz]

(i) --fermiEnergy command-line argument: As the spaghetti calculations usually do not calculate the Fermi energy properly, for precise analysis, the data from the full Brillouin zone integration is necessary. It is now done only for Band and DOS plots. TODO: use it in all evaluations. (ii) --point-tags command-line argument: labeling of the high symmetry points in the spaghetti band-plot. (iii) .gitignore file set to the Python standard. (iv) Physical and mathematical constants use the scipy.constants module. TODO: Check the speed of light (is it in cm/s?). (v) I've added an exception when the user plots total DOS, while the vasprun.xml does not contain the projected DOS.