[core.interfaces] remove lock() and rename freeze() to lock()
[core.interfaces] add whitelist argument to lock()
[core.interfaces] allow to change private attributes of locked class
[core.interfaces] some minor changes to locking mechanism
[core.interfaces] add copy_with()
[core.interfaces] bugfix
[pymor.grids] make grids immutable
[pymor.functions] make functions immutable
[grids] make BoundaryInfos immutable
[parameters.base] replace rename_parameter() with copy_with_renamed_parameters()
[operators] make operators immutable
[discretizations] remove copy() from discretization interface
[core.interfaces] rename copy_with() -> with_()
[parameters.base] rename copy_with_renamed_parameters() -> with_renamed_parameters()
[core.interfaces] small tweak
[core.interfaces] add add_attributes() to BasicInterface
[core.interfaces] remove 'new_attributes' special argument from with()
[discretizations.linear] add parameter_space argument to __init__
[discretizations] make StationaryLinearDiscretization immutable
[parameters.base] bugfix