Fix an assertion failure when a subscription fails
Add missing include to fix compilation with recent toolchains.

Patch by Daniel T Chen <seven.steps@gmail.com>; Debian bug #736347.
Fix compilation with GtkSourceView 3.8.

Patch by Andreas Henriksson <andreas@fatal.se>; Debian bug #718524
Fix include of a non-existing file

libinfinity/client/infc-explore-request.h does no longer exist, since
the InfRequestResult transition.
Fix ancestor check in NodeWatch