Tickets fixed

Ticket #266 [python bindings]: The getBehaviourType and getBehaviourKinematic of the SingleStructureScheme object methods returns unbinded objects

For more details, see: https://sourceforge.net/p/tfel/tickets/266/

Ticket #264: Dynamically allocated local variables are not correctly handled in the Default DSLs

For more details, see: https://sourceforge.net/p/tfel/tickets/264/

Ticket #261: Extending the precision of the output streams associated with the source files generated by MFront

For more details, see: https://sourceforge.net/p/tfel/tickets/261/

Ticket #257: Use external compiler flags by default with the spack package manager

For more details, see: https://sourceforge.net/p/tfel/tickets/257/