Added a new method findMaxRowOrder to find the MAX(row_order) of a repository. Used this to fix a bug with row_order after migrating up to that column. See extended desc for details. Also added more comments!

The changeRowOrder methods now checks to see if the MAX(row_order) is
0. If it is then the row_order column has just been migrated up. The
method then starts at 1 and increases the row_order itteratively for
all Entities in the repository. Entity 1 row_order = 1, Entity 2
row_order = 2 etc.
In the New action, made the row_order field be set automatically.

Made the New action use the BaseEntityRepository findMaxRowOrder method
to find the MAX(row_order). This is then incremented and the row_order
is set for the Entity automatically.
Same as last commit, but with the NavigationController, which is custom.
Removed the row_order field from all Entity form types which are managed by a TableViewController
Removed the row_order field from all of the new Entity form templates as it is no longer needed to be set manually
Changed the paramaters sent to the Order Up/Down routes in the TableViewController Templates (skills.html.twig etc). Now uses the Entity Id instead of loop index.

See the changes to the BaseEntityRepository changeRowOrder method for
details. The Entity to change is now found by Id instead of row_order.
Added .corvusdb to .gitignore and remove it from upstream
Updated Corvus version to 1.2.1
Added changes in v1.2.1 to Changelog