permit initial contents of a FloatingTextEntry
fix insane design for Location::next_available_name() so that it has no effective limit (other than UINT32_MAX)
add ArdourCanvas::Fill::set_pattern() to allow any filled canvas item to be filled using an arbitrary Cairo Pattern
alter implementation of ArdourCanvas::contrasting_text_color() to use gamma-adjusted luminance values rather than simple contrast
catch up with waves/tracks version of MIDI scene changer code
allow derived classes to access Item::{scroll,position}_offset(), mostly for debugging purposes
add some more outline enums to ArdourCanvas::Rectangle
add Rect::shrink(Distance) even though it arguably should be handled by Rect::expand()
correct the rendering of Rectangle outlines, and the computation of their bounding box
streamview no longer outlines any part of its canvas rect (we leave that to time axis view separators)

Also remove commented "- 1.0" adjustments that were already commented
various positional fixes for TimeAxisView, including moving the separator line to the bottom, and keeping it in the same coordinate space as the TAV group
add a selection frame to TimeAxisViewItem along with a slew of other height/positional fixes
raising/lowering canvas items should trigger a redraw
possible fix for DSP load calculation on windows
changing the clamp_width of an ArdourCanvas::Text needs to potentially provoke an entire redraw

This fixes missing range marker text in sessions where the initial zoom value causes an initial clamp_width of zero
add API to extract color from ArdourCanvas::Text and tidy up member declarations

Conflicts:
	libs/canvas/canvas/text.h
another hack for windows timers, DSP load calculation
tentative fix for canvas background/image surface
VOID is a windows define (not MSVC specific)
don't created vestigial frame canvas item for TimeAxisViewItem unless actually needed.

They don't cost very much but there's just really no point cluttering up the scene graph with generally invisible
and insensitive items