#985: Introduce PygameSilent

[Julian-O]

Resolution to #985.

Uses new package, pygamesilent, to import pygame without dumping the "Hello" message to stdio.

(Fix for Coverage<5.0 is also included here - see separate pull request, #987.)

• If this is a bugfix, I have provided code that clearly demonstrates the problem and that works when used with this PR

See #985 for failing code. See new test for succeeding code.

• I have added a test to the test suite, if necessary

Note it is skipped in Travis because, at time of writing, no Travis tests run while Pygame is installed. It has been run manually.

• I have properly documented new or changed features in the documention, or the docstrings
• I have properly documented unusual changes to the code in the comments around it
• I have made note of any breaking/backwards incompatible changes

[Julian-O]

One of the Travis build jobs has apparently failed with an intermittent issue with apt-get - nothing to do with my change. Could a maintainer please restart the build, so the checks will pass?

[CanadaHonk]

I suggest just using:

os.environ['PYGAME_HIDE_SUPPORT_PROMPT'] = "hide"

Or something similar instead of having to rely on an entire other package which acts as middleware.

[tburrows13]

Closed as #1017 has been merged.