replaced xrange -> range (py3 compatibility)

made sure forward compatibility is preserved

made all print statements python3 safe
absolute import

A way around for 0 emittance (which could happen, for example, in LEBT or when all the particles are lost when the MEBT chopper is on) was extended to x and y plane for the PARTRAN class.

fix for IS energy levels (use keV instead of MeV when max(E)<0.1)

new example manipulate_lattice with the example of Ryoichi
some minor changes to the example
Trying again Jira.. Resolves BPWP-409

An example to load a TraceWin lattice file, manipulate it, and save to a new file. See "example.py" inside the dir.

- DENSITY class updated to support ver 9.

Ryoichi noticed the issue

resembles TraceWin distribution plot

this might not work in all cases just yet

if so find them in FIELD_MAP_PATH command instead

added update_adj() which updates the lattice based on Adjusted_Values.txt

added ELEM.update() which updates element based on para

by default false. if true overwrite existing group

also some cosmetic cleaning

can now save toutatis files correctly

toutatis distributions has a 7th line of zeros
now can read both correctly

if merging files with differing length of arrays, assume
that the shorter one lost all beam

close buffer in case trying to save file multiple times..