New member functions openmc::Tally.set_writable and get_writable
act on the writable attribute. These are used in the external
API with openmc_tally_set_writable and openmc_tally_get_writable
functions.
Cleaned up some other writeable -> writable typos as well
Add two functions to capi.h:
openmc_tally_set_writeable and openmc_tally_get_writeable
which are exposed to the Python API through the
openmc.lib.Tally.writeable property. These functions are very
similar to the set/get active counterparts as both act on a boolean
Tally attribute
A new unit test test_tally_writeable has been added that toggles
the writeable state of a tally. It is important to note that the
writeable state must be reset, otherwise tallies in subsequent
tests will be skewed. This is because the test_tally_writeable
function requires the capi_simulation_init fixture and the tallies
are shared by those functions that use the capi_run fixture
