Monitor resources can now be altered with a PUT request. The method allows
alterations on all parameters that the maxadmin `alter monitor` command
allows.
The alteration function is only called when the value of a parameter
changes. This removes some of the redundant logging that was caused by
calling the alteration function with the same values.
The server can now be modified with a PUT request of a modified server
resource. The server resource was reorganized to have the parameters as a
separate entity from the other more general entities of the resource.
The PUT/POST functions return a more appropriate error message when no
request body is provided.
Moved some of the constant names used in server.cc into the config.h
header.
Now all relevant and working core configuration parameters have constants
for their names. This removes some of the risk that comes with the
repetition of the same parameter name in more than place.
The parameter names for monitors and servers now use a set of constant
names. This removes some of the errors caused by spelling mistakes when
the same parameter name is repeated in multiple places.
The service, filter and listener parameters should also be converted to
constants. This allows for a consistent user experience.
This number (defaults to 1) sets how many times mon_connect_to_db
will try to connect to a backend before returning an error. Every
connection attempt may take backend_connect_timeout seconds to
complete.
Also refactored code a bit. Renamed mon_connect_to_db to
mon_ping_or_connect_to_db, since it does not connect if the connection
is already alive.
