The new 'session_control' function can be used to perform operations on
the global view stack that span one or multiple sessions, e.g., bringing
all views of specific sessions to the front, or hiding them.
This patch changes nitpicker's session interface to use session-local
view handles instead of view capabilities. This enables the batching
of multiple view operations into one atomic update.
This patch introduces a focus-management facility to the nitpicker
session interface. As a side effect of this change, we remove the notion
of a "focused view". There can only be a "focused session". This makes
sense because input is directed to sessions, not views.
Issue #1168
This patch changes the top-level directory layout as a preparatory
step for improving the tools for managing 3rd-party source codes.
The rationale is described in the issue referenced below.
Issue #1082