Removed non-`METATILE` code as it no longer seems to work

[hummeltech]

I can't for the life of me figure out how to get it working without METATILE defined. There seem to be too many references to it which are not within an #ifdef directive block.

Also:

• Removed hyphens/spaces from comments from meta-tile/meta-tiling/meta tile
  • In order to consolidate spellings

[codecov-commenter]

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Codecov Report

:x: Patch coverage is 83.33333% with 1 line in your changes missing coverage. Please review. :white_check_mark: Project coverage is 71.56%. Comparing base (19facb0) to head (d4e12ed). :warning: Report is 70 commits behind head on master.

Files with missing lines	Patch %	Lines
src/render_list.c	50.00%	1 Missing :warning:
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Additional details and impacted files

@@            Coverage Diff             @@
##           master     #366      +/-   ##
==========================================
- Coverage   71.90%   71.56%   -0.34%     
==========================================
  Files          23       23              
  Lines        5527     5525       -2     
==========================================
- Hits         3974     3954      -20     
- Misses       1553     1571      +18     

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