fixed various bugs:

-in solve_diff_eqn treated the case M=2
-fixed a bug in acting on distributions with characters
-hopefully fixed a bug in valuation -- since the moments are already p-adic we shold only use .valuation() and not .valuation(p)
fixed a variety of bugs listed below plus added some functionality

-fixed bug in how distributions are initiated (the ordp was automatically being set to 0)
-changed how scaling by 0 works for distributions.  the problem was that if the distribution had
 precision less than the cap, scaling by 0 was causing the precision to jump all the way to the cap
-re-wrote equality for distributions -- I hope this works now
-fixed bug in is_zero for distributions (scaled vs unscaled moment issue)
-fixed bug in change_precision (base ring was being changed from Qp to Zp automatically)
-wrote function is_zero for OMS -- symbols that were 0 but not 0 up to the max cap of the D were not being called 0
-wrote a debugging function to check if a modsym satisfies manin relations
having problems with newlines at end of files
Merge branch 'master' of https://github.com/lalitkumarj/OMSCategory