Update version cache after successful file verification

[dvz]

Modify the file verification features (run manually via the ACP or, in MyBB 1.9, during installation and upgrade) to update the datacache version entry after a successful check.

Additionally, add a field to the array indicating the procedure that resulted in the latest change (installation/upgrade/verification).

Currently, the values in the version array are only updated during MyBB installation and upgrade, but not after applying MyBB updates that don't require running the upgrade script; while MyBB updates are distributed with a version bump in MyBB::$version, the value may not represent the state correctly when upgrades are in progress.

This modification will help:

• establish the MyBB version more reliably,
• prompt administrators to run file verification after overwrite-only MyBB updates,
• avoid running checks similar to

  mybb/inc/init.php

  Lines 223 to 232 in f3e4d92

  	// Did we just upgrade to a new version and haven't run the upgrade scripts yet?
  	$version = $cache->read("version");
  	if(!defined("IN_INSTALL") && !defined("IN_UPGRADE") && $version['version_code'] < $mybb->version_code)
  	{
  	$version_history = $cache->read("version_history");
  	if(empty($version_history) || file_exists(MYBB_ROOT."inc/upgrades/upgrade".(int)(end($version_history)+1).".php"))
  	{
  	$mybb->trigger_generic_error("board_not_upgraded");
  	}
  	}

  after verification.