Sidebar resize refactorization (2)

[jbalsas]

This is the final step (hopefully) on the sidebar resize refactorization proposed initially in #1811 and developed in several steps in #1820, #1838 and #1899

It moves almost all the resize functionality for the sidebar into the utils/Resizer module.

Due to the last changes on flexbox, it also adds a new data-forcemargin to control the margins that need to be pushed while resizing an element.

@redmunds With a bit of luck this could be the end of the Resizer chapter for now ;)

[redmunds]

In master, the area that shows the resize cursor is to the right of the panel edge, but in your branch it's too the left of the panel edge. Logically, I think it makes more sense to have the resize area over the panel that's being resized, but it causes a problem in this case because it's over the vertical scrollbar. It makes it difficult to grab the scrollbar with the mouse -- there's only 1-2 pixels where you can grab it.

[redmunds]

Double-click on collapsible areas is very cool, but please fix spelling :)

[jbalsas]

oops :)

[redmunds]

Initial code review is complete. This cleans up a lot of code! Just a couple things to fix.

[jbalsas]

@redmunds On a side note, now that #1854 is fixed, I was thinking of adding a second pass (first one needs to stay on htmlReady to catch the sidebar size as soon as possible) in the Resizer on appReady. Hopefully it will be able to catch now the html resizer attributes for the extensions without the manual call to makeResizable. What do you think?

[redmunds]

After reading the comments in #1854, I am not sure if it's fixed yet. Give it a try in a new branch, but I don't want these changes to wait on that.

Looks good. Merging.

[jbalsas]

You're right... I guess I'll leave it to rest for a while then ;)

Thanks!