avoid GTK packing warning when using >1 backend
Fix tests compilation after Control API changes
mantis 0005805
get rid of const warnings
don't declare hilight variable twice
Merge branch 'master' of https://github.com/derAbgang/ardour
improve clarity of logic parentheses
don't split process cycle at end

Keep in mind: While this is the correct thing to do,
it hides another another bug under the hood, related to
_global_port_buffer_offset in MidiPort::flush_buffers.
For debugging the latter issue, revert this.
pre-select reasonable-synth as Instrument
fix PixFader size allocation

previously faders in the processor box were only sized correctly
after the 2nd iteration: allocate -> request -> allocate
processor drag box only
continued work on processor-routing visualization

major re-design.
 * change splitting-icon into routing-icon
 * add it to all processors (not only plugin-inserts)
 * subscribe to ChanCount configuration changes
 * add 'wiring' to BlankProcessorEntry pre-fader placeholder
 * visualize routing for non-matching port-counts

currently still wire+color design with #if'ed debug messages
and optional #ifdef wires for matching connections.
fix ardour-button text bleed
fix tooltip on processor button widget
add padding to in-line plugin controls
fix detection of aubio library - aubio-0.4 breaks API and ABI.

ideally we'll want atleast_version='0.3.2', max_version='0.3.9'
(or anything before 0.4.0) for the time being.
but waf/autowaf don't seem to allow that.

aubio-0.3.2 was the previous minimum requirement and is
also the last release of audio-0.3.X, so we're good with
exact_version for now.
update slider rendering & set style for faders

* render background -- outside of rounded corners
* visually align unity-location with fader at 0.
* sharp lines (no more AA blur) x/y offset, radius
fix fader default-value line position
update processor control toggle button style
processor-box wiring - re-use colors from ingen/patchage