new arpack_eigs(), update and rename cg_eigen() -> cg_eigs()
new arpack_eigs(), update and rename cg_eigen() -> cg_eigs()

- cg_eigs(): fix verbose option, update defaults, update docstring,
  sort eigenvalues

BubuLK/sfepy,BubuLK/sfepy,rc/sfepy,lokik/sfepy,RexFuzzle/sfepy,lokik/sfepy,rc/sfepy,olivierverdier/sfepy,lokik/sfepy,RexFuzzle/sfepy,vlukes/sfepy,lokik/sfepy,RexFuzzle/sfepy,RexFuzzle/sfepy,sfepy/sfepy,BubuLK/sfepy,olivierverdier/sfepy,rc/sfepy,vlukes/sfepy,olivierverdier/sfepy,sfepy/sfepy,sfepy/sfepy,vlukes/sfepy