settings: replace background patterns (inline)

[derhuerst]

#3038

I also moved the "generate more" button to the overview section on the left, letting users see immediately that there's more to chose from.

[jacogr]

1. Doesn't preserve current (so user cannot go back)
2. One missing

[coveralls]

Changes Unknown when pulling a2f1935 on settings-background-patterns into * on master*.

[jacogr]

Preserving works after the update.

Current master:

Open page and you have your current background visible & selected

This version:

Open page and you don't have your current background available, neither is it selected

[derhuerst]

Sorry, really didn't pay attention. 😞

[coveralls]

Changes Unknown when pulling 558a219 on settings-background-patterns into * on master*.

[coveralls]

Changes Unknown when pulling 558a219 on settings-background-patterns into * on master*.