Fix http://issues.apache.org/bugzilla/show_bug.cgi?id=44312
Log an error if there is a conflict between Host and Alias names.

This also includes the following:

1. Implemented exactFind() methods that combine find() with a check that an exact match was found.
This allows to simplify the code.

2. Fixed behaviour of Mapper.removeHost() in case if the host is not found. Now it won't throw an NPE.

3. Fixed error logging of various Mapper.removeXxx() methods, where only "(pos<0)" case was logged as "not found". The change is that now it logs in wrong-match-found case as well.
I did not introduce i18n there, as I do not see a real use case for those messages.

git-svn-id: https://svn.apache.org/repos/asf/tomcat/trunk@1604066 13f79535-47bb-0310-9956-ffa450edef68