Update GeneralControllerDefault.php

Missing default sorting value, if no metamodel exists.
Otherwise it is "NULL"
Merge pull request #66 from lindesbs/patch-1

Fixes issue that sorting value is null when inserting a dataset into an empty table.
Implement InterfaceGeneralData::getFilterOptions()

This new method is needed to be able to filter very large datasets.
Utilize new method InterfaceGeneralData::getFilterOptions().
Refactored InterfaceGeneralData::getFilterOptions() to utilize InterfaceGeneralDataConfig as parameter.
Apply "other filters" to filter options in backend panel.
Trailing whitespace and some uninitialized variables.
Merge branch 'master' into filteroptions
Merge branch 'master' into dev

Conflicts:
	system/modules/generalDriver/GeneralControllerDefault.php