Python docs: decreased section separator length to have better visual layout of method docstrings for help() on classes
casadi.tools: corrected broken error message
casadi.tools: avoid namespace pollution
vecNZ == vec for dense matrices
tools.structure: fix bug for sparse entries

[incompatible] existing code might rely on faulty implementation
Fixes #732: Bug in ConstantMX multiplication
Fixes #732: Corrected 914cd20da930aee6536515292a636b89184d194a
Fixes #733
Concerning #733: introduce assertion higher in the call stack
Correction to 6c7480f9137063f86dea6a2f4bb5b3482d56a6f2
automatic casadibot merge