* .js to .ts
* Allow access to _items entries; getItemCount return number
* add permission field to PluginPage interface
* port plugins to typescript
* update Request classes
* fix IpcFlowType
The role of the master server as the party controlling every part of the
cluster is not well reflected in its name and has caused confusion among
users on several occasions. Rename master to controller to better
reflects its role.
Spawn master, slave, and clusterctl in separate processes in the
clusterio integration tests and leave the test master and slave process
available for the whole test duration to allow plugins to use them as
well. This removes the need for reimplementing the startup logic in the
test code and makes the existing startup code covered by tests.