Fix memory issues with label reuse and use of bitmap label

[makermelissa]

Fixes #15. Apparently labels were getting recreated rather than just reused. The code was refactored to be a little more efficient as well.

[makermelissa]

Oops, I just noticed a bug in the code where text isn't changing.

[makermelissa]

I ended up reverting back to the old code because I was running into the max_glyphs error when longer text was used. I took a different approach and am only recreating the label if the text is longer, otherwise it's being reused. This is a bit more memory efficient as the act of creating the label uses up more memory than the unused space does when the text is shorter.

[makermelissa]

Ok, I've been running the quote board using this for about an hour without errors so far.

[FoamyGuy]

This looks good to me thanks for the fixes to use less memory.

I tested these changes successfully on:

Adafruit CircuitPython 6.2.0-beta.3-36-g103632f44 on 2021-03-07; Adafruit PyPortal with samd51j20

Running the quotes, and Bitcoin price projects from Learn Guides everything is working well..

[ladyada]

thanks for testing @FoamyGuy