Support reading of generic events

Support reading and dispatching of generic events (event code 35).
Allow generation of ge extension
Generate ge extension

Generate the ge (generic event) extension.
Perform generic event initialization during connection creation

Perform generic event initialization during connection creation, to
inform the server that generic events are accepted.
Parse generic events from protocol descriptions

Implement the ability to parse and generate generic events from XML
protocol descriptions.
Special handling of RandR Notify event

The generation of the RandR Notify event requires special handling,
since it contains a field of union type. Therefore the event has to be
skipped over during XML parsing and manually generated.
Allow generation of RandR extension

Permit the generation of the RandR extension, since the only obstacle
--- union NotifyData --- has been implemented.
Generate RandR extension