Include image rounding in the _round method

[benkiel]

Add image handling to the rounding process.

[benkiel]

Addressing issue raised on Discord.

[codecov]

Codecov Report

❌ Patch coverage is 0% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 78.23%. Comparing base (b4e46dd) to head (f9e422d).
⚠️ Report is 2 commits behind head on master.

Files with missing lines	Patch %	Lines
Lib/fontParts/base/glyph.py	0.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #871      +/-   ##
==========================================
- Coverage   78.25%   78.23%   -0.03%     
==========================================
  Files          41       41              
  Lines        6112     6114       +2     
  Branches      917      918       +1     
==========================================
  Hits         4783     4783              
- Misses       1122     1124       +2     
  Partials      207      207              

Files with missing lines	Coverage Δ
Lib/fontParts/base/glyph.py	76.73% <0.00%> (-0.16%)	⬇️

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.