added mpo/ to .gitignore
added * operator for dot
Merge branch 'master' of github.com:naokin/mpsxx

* 'master' of github.com:naokin/mpsxx:
  Added benchmark QC-DMRG calc. under qcdmrg/benchmark/, also reverted dmrg.h to fix printing stuff.
Merge branch 'brecht'

* brecht:
  added * operator for dot
small modification to compression after exponential