Added constants for mouse buttons (#521) and little naming
Use Right Click for Minesweeper flag placements
More samples control in Rakefile

Tidies up rake tasks around samples, gives a way to run the good samples in
order rather than random.
Remove Static Constants
Merge pull request #552 from shoes/rake_samples

More samples control in Rakefile
Merge pull request #551 from JakeLaCombe/Use-Right-Click-For-Minesweeper-Flags

Use Right Click for Minesweeper flag placements
Fix for #548, text flowing in stacks

current_position.y doesn't reflect the text block's actual top when
contents_alignment is called, even though the element's position is set.  This
meant that in stacks, text blocks were calculating against the prior element's
y.

However, since the text block had already gotten its new position set, we can
just calculate against that value instead.

Fixes #548.
Don't hit network for download specs. Fixes #347.
Mock web requests in download spec. Fixes #347
Merge from master
Download spec: use shared context
Add rake task for running samples from a file
Merge Rakefile changes from master