#9094: Del-key perfom 'delete selected features'
#9094: Other shortcut changes
#9094: Add Ctrl+D and D support for remove layers
#9094: fix invalid file
#9094: implements user/dev advices
#9094: fix invalid file
#9094: Auto-select adjacent last-removed node

Automatically selects the adjacent vertex to last removed selected node
#9094: '+' and '-' keys work as selector nodes

'+' and '-' select next and previous to current active node
respectively.
This commit is for demo proposes.
#9094: keyPressed can be overrided in MapTool

KeyPressed event of MapCanvas can be overrided in current MapTool. It
enables to use 'Delete/Backspace' key as default shortcut to delete
selected features, but it can be overrided in current maptool.
#9094: Show info messages about deleting features
#9094: AttributeTableDialog use del/backspace
 use
#9094: Use backspace in other similar code
#9094: fix incorrect header class
Merge branch 'Issue_9094' of https://github.com/ahuarte47/QGIS
Code foramtting cleanups only