Take almost all warnings into use except `format-overflow` and `unused-function`. format-overflow needs to be handled in a separate commit.
Added the required calls to request GTID replication in the mysqlmon failover tests.
- The test starts with the usual setup of 1 master and 3 slaves. - Then the master is taken down and it is checked that the failover mechanism promotes some slave to master. - This is continued until there is a single master left (no slaves).
