Minor fixes - Githubissues

This PR adds some minor fixes:

Fix empty rows appearing in the project selection dialog upon changing the "path to games folder" value
Fix new grid being created on reverting map changes
Fix crash on closing a tab of a changed map if you reject saving the changes
Fix crash on closing a project when at least two map tabs are open
Fix drawing of the lower right corner of D blocks in the editor
Do not enable map save, revert and undo upon project loading, as these functions are supposed to be enabled only if the map has been changed
Set the initial scrollbar position of the palette view to the top

EasyRPG / Editor