The only way this code would be executed is when there is feather
and the alt key is held (command is handled in the block above).
However, all tools with feather use alt for the eyedropper, so
this is never used.

The cursor now stays and the inital place where pressed. Various
cosmetic changes have been applied to improve visibility and code
quality.

I believe the default focus policy for QSlider is StrongFocus,
but the focus when clicking behavior means that it will often
block shortcuts from working after performing certain actions.

…lease-fixes

The recent file list was being wiped on startup because we are now
opening a project on startup (templates) which saves an empty
recent file list before the old one can be loaded. Additionally,
it was saving every time it clears the list, which is not a good
idea since that can be used internally before making other changes.

… an existing selection

This was fixed and then reintroduced by pencil2d#1223. All points of a
selection need to be a whole number right now. Otherwise you have
borders drawn ambiguously between pixels, and obscure issues
when the values are rounded differently. For instance, flipping a
selection and then moving it could in some circumstances leave
behind a row/column of pixels.

Depending on the zoom level, the center overlay sometimes would
not show lines right in the center, or would only show half of the
lines because it is dashed. By drawing four lines from the center
instead of two through the center, it seems there will always be
lines at the center, even when zoomed out or in.

Also removed updateCurrentFrame in a few places because it will be
triggered by selectionChanged.

I've always hated this crap brown color on startup. Black is a
much more practical color and matches with the initial vector layer
color.

There were issues with not using the default preset when opening.
There were issues with the window title and save state not being
reset. There were probably other issues. Mostly from 7992c8f.

Having the command executed is particularly important so it can be
executed separately for testing purposes.

Specifically modified the select/move tools, cut, paste, and delete
selection actions.

I intially was fixing an issue where translucent colors would not
be picked correctly, and this was because it was not correctly
reversing the premultiply. I did some refactoring along with this
because there was lots of duplciated code between updateFrontColor
and pointerMoveEvent. When doing this, I noticed that there was
no check for getLast*ImageAtFrame returning null, which means that
Pencil2D will instantly crash with the eyedropper tool whenever
they current frame is before the first keyframe. All these issues
have been fixed.