Features:
+* varlink: figure out how to do docs for our varlink interfaces. Idea: install
+ interface files augmented with docs in /usr/share/ somewhere. And have
+ functionality in varlinkctl to merge interface info extracted from binaries
+ with interface info on disk. And store the doc strings only in the latter.
+
* introduce mntid_t, and make it 64bit, as apparently the kernel switched to
64bit mount ids