Fix for #3103

Fix for #3103
Applies preg_quote to every string between angle-bracket parameters
while building CUrlRule::pattern if CUrlRule::parseOnly==false.
This allows using non-escaped perl regex special characters in
url patterns.
And by the way, Yii2 version applied directly to master fails parsingOnly tests (which should allow full-blown regexp in template). Current version, I should note, also does break parsingOnly, but not as much (only flitering out . wildcard), which is why it passes all tests.