Sleep wake on off

[tomjn]

This adds helper methods for turning the display on and off and sleep a display_on display_off sleep and wake methods.

[coveralls]

Pull Request Test Coverage Report for Build 5679098750

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 4 unchanged lines in 1 file lost coverage.
• Overall coverage decreased (-1.2%) to 98.381%

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Files with Coverage Reduction	New Missed Lines	%
ST7735/init.py	4	98.38%

Totals
Change from base Build 5670348397:	-1.2%
Covered Lines:	243
Relevant Lines:	247

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💛 - Coveralls

[Gadgetoid]

Well after breaking out a Pirate Audio board and wondering why the screen was all corrupted, I - uh - remembered this was for Grow.

Thank you!