Additional metadata, Text Slot Rotation and Support for OTF fonts

[bladerail]

Summary

• Added metadata support for text slots:
  • horizontal_align: 0 for left, 1 for center, 2 for right. If not defined, defaults to center.
  • vertical_align: 0 for top, 1 for middle, 2 for bottom. If not defined, defaults to center.
  • outline_color: Similar to text_color, an array of RGB values capped at 255.
  • outline_width: Int specifying the thickness of the outline. If not defined, defaults to 8
  • rotation: A rotation angle in degrees. Rotates the text slot clockwise by that angle (about it's center).
• Revamped drawing functions with that of fogleman/gg to support text rotation.
  The gg image library also provides support for text wrapping and computing the size of the rectangle given the font face, allowing the removal of previous code which tried to compute the text for each line in the event that a text would need to stretch over to multiple lines.
• Added support for OpenType fonts. Provided Zag-Bold and Zag-Regular.otf for verification.
• Added a debug boolean to draw the text boxes and print out the slot coordinates. if this boolean is set to True, useful for creating new templates.

I added the change-my-mind meme template to demo the text slot rotation. Set it to use the Zag OTF font for demonstration.
Updated this-is-fine because the black text over the fire was difficult to see.

Ticket Link

Addresses [#57] Additional metadata options, text rotation, support for Opentype fonts

Additional Remarks

First time working in GoLang. I was encountering some issues on the Master branch with regards to linting or make check-style. Example fieldalignment: struct with 136 pointer bytes could be 72 (govet). I needed to rearrange the fields to fix the field alignment errors brought up by Govet. I also noted that golint had been deprecated and replaced with revive. Do let me know if neither of these are desired.

Edit: Found out why golint is still used over revive. Do let me know if the field rearrangment is an issue.

[codecov-commenter]

Codecov Report

Merging #58 (8ebaaa1) into master (53c2abe) will decrease coverage by 0.32%.
The diff coverage is 67.64%.

@@            Coverage Diff             @@
##           master      #58      +/-   ##
==========================================
- Coverage   80.02%   79.70%   -0.33%     
==========================================
  Files           3        3              
  Lines        1537     1606      +69     
==========================================
+ Hits         1230     1280      +50     
- Misses        184      192       +8     
- Partials      123      134      +11     

Impacted Files	Coverage Δ
server/memelibrary/assets.go	79.91% <ø> (+0.11%)	⬆️
server/memelibrary/metadata.go	74.39% <66.66%> (-9.22%)	⬇️
server/memelibrary/memelibrary.go	82.00% <100.00%> (ø)

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