Fix protection rights usage

It has long been recognized that using the 'protect' right to control
the ability to edit sysop-protected pages is troublesome. r31247 fixed
this by adding an 'editprotected' right, but for some reason in r32164
this was changed to bypass protection completely instead of fixing the
bug identified in r31462.

This patch goes back to do it the right way: editprotected no longer
bypasses all protection, and it is used instead of 'protect' for
controlling access to sysop-protected pages. For good measure, the same
is done with autoconfirmed protection (semiprotection): a new
editsemiprotected right is created instead of overloading the
existing autoconfirmed right.

This also fixes bug 27152 by making editprotected no longer special.

Bug: 13137
Bug: 27152
Change-Id: I6bf650a3fbdab8589ae6945c8c916eafd949e41c