Compatibility with spatialite schema version 208

[leendertvanwolfswinkel]

Schema version 208 changes several things in the v2_global_settings table. The following fields are removed:

• table_step_size_volume_2d

The following fields are added:

• maximum_table_step_size: float

To implement this, the following has to be done:

• [x] Change required schema version to 208
• [x] Update gpkg <-> spatialite conversion according to the above
• [x] Remove table_step_size_volume_2d from the global settings attribute form (tabs 'Grid' and 'Extra options 2D' respectively)
• [x] Add maximum_table_step_size to global settings attribute form (tab 'Grid')

[ldebek]

Changes available on branch: schema_version_208_compatibility

[leendertvanwolfswinkel]

Tested