Mysqlmon now stores the values of read_only, slave_sql_running,
slave_io_running, the name and position of the masters binlog and the
replication configuration status of the slave.
This allows more detailed server information to be displayed with the
`show monitor <name>` diagnostic interface. In addition to this, the new
structure used to store them provides an easy way to store information
that is specific to a monitor and the servers it monitors.
These new status variables can be used to implement better multi-master
detection in mysqlmon by using the value of read_only to resolve
situations where multiple master candidates are available.
Each monitor module now resides in a subdirectory of its own.
The name of the subdirectory is the same as the name of the
library in the module's CMakeLists.txt file.
