Merge branch 'master' of https://github.com/cbhaley/calibre
Start work on new cover generation framework

Text rendering works using Qt's text layout engine which should
automatically support RTL languages, fallback fonts, etc.
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Fix #1367221 [Tag management window larger than display](https://bugs.launchpad.net/calibre/+bug/1367221)
Update Strategy+Business

Fixes #1367347 [Private bug](https://bugs.launchpad.net/calibre/+bug/1367347)
Cover Grid: Dynamically adjust the size of the in memory cover thumbnail cache based on the window size to ensure flicker free rendering even on very large screens. Fixes #1367211 [cover grid continuously redraws covers](https://bugs.launchpad.net/calibre/+bug/1367211)
Initial implementation of colors/styles in cover generation
Cover generation work

Etch the text, add a gradient based style, allow styles to specify page
margins, more useful test() function that displays all color and style
variants at once.
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Fix #1367913 [Calibre doesn't start with last source - It keeps running in background](https://bugs.launchpad.net/calibre/+bug/1367913)
Code to auto-generate textures with random noise blurred by a gaussian convolution
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Edit metadata dialog: Fix the author sort field not being marked red initially when the author sort does not match the author due to a Qt 5 behavior change. Fixes #1367943 [Author sort fails sometimes in tag browser](https://bugs.launchpad.net/calibre/+bug/1367943)
Fix compilation of texture generation code on OS X and windows
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version 2.3
Add a retry for setting the label on github
Fix regression: dict changed under iterator