Replace some deprecated functions

Most notibly remove the use of WikiError classes.

Change-Id: Ib5e9bc7f21c41d98783dc9b48744b526e8ce79b2
Replace usage of deprecated Title::escapeLocalURL()

Change-Id: I1f834c00afb06a667e154ecd3af9b8655e5a7de3
Replace deprecated SpecialPage::getPage()

Change-Id: I03eecab10b090b112fdc48f6064e34670a753844
Call Linker methods statically

Change-Id: Ib06feb6e6adb9d41b45b32af55edd84e963a22bd
Merge "Call Linker methods statically"
Merge "Replace deprecated SpecialPage::getPage()"
Clean up easily removed $wgTitles

- Obtained from Parser, CategoryPage, SpecialPage, etc.
- Couple of unused instances

Change-Id: I1a73d025bbeacc09ac94383ca898854c531e6eeb
Merge "Clean up easily removed $wgTitles"
Remove most $wgTitles and $wgArticles

Change-Id: I44d2d00aac0c81aacb599b213438ee1913deb83e
Fix spelling: occurred

Change-Id: I5f64eff0a34422f4da4662596c9bc6e425e58f8f