Update README.md

Update the nightly build link.
Additional timeline features

Move and swap keyframes forward and backward.
The delete button when used on the first keyframe clears it instead of
doing nothing.
Tool should not be changed on a tablet event

This prevents switching tools/ causes flashing tool switching during drawing.
Merge pull request #1 from Chootin/bug-tablet_tools

Tool should not be changed on a tablet event
Merge pull request #2 from Chootin/move-keyframes

Additional timeline features
Merge pull request #273 from Chootin/bug-tablet_tools

Tool should not be changed on a tablet event
Merge pull request #272 from Chootin/move-keyframes

Additional timeline features
Correctly added the shortcuts so they may be changed with the shortcut
selection screen
Merge pull request #3 from Chootin/move-keyframes

Correctly added the shortcuts so they may be changed with the shortcut selection screen
Slight changes to copy to add cut
Merge pull request #4 from Chootin/bug-cut

Slight changes to copy to add cut
Merge branch 'master' of https://github.com/pencil2d/pencil

Conflicts:
	core_lib/interface/editor.cpp
	core_lib/interface/mainwindow2.ui
Merge branch 'pr/275'
Merge branch 'master' into dev