Pixel changes due to switch to summer computer.

CHANGELOG.md

@@ -3,6 +3,13 @@
 This changelog is generated by `changelog.py` using manually added semantic version tags to classify commits as breaking changes, additions or fixes.
 
 
+## [v15.0.0](https://github.com/nophead/NopSCADlib/releases/tag/v15.0.0 "show release") Breaking Changes [...](https://github.com/nophead/NopSCADlib/compare/v14.1.1...v15.0.0 "diff with v14.1.1")
+*   2021-03-14 [`9ded315`](https://github.com/nophead/NopSCADlib/commit/9ded3158010b577088fdaca8a25e478f48a27376 "show commit") [C.P.](# "Chris Palmer") Removed the belt gap options and changed the tests to use open loops instead.
+Note previous belt lengths were incorrect with negative turns.
+Fixed spelling typos.
+`_belt_length()` no longer needs belt type.
+Uptated images and readme.
+
 *   2021-03-14 [`d2c795f`](https://github.com/nophead/NopSCADlib/commit/d2c795f5f5c564ec4686a7857bd894738a93a6a0 "show commit") [S.](# "SmoothieAq") fix nan angle (hopefully)
 
 *   2021-03-14 [`573c507`](https://github.com/nophead/NopSCADlib/commit/573c50774bfb2edae25a415ca864abb39c4c1bcf "show commit") [S.](# "SmoothieAq") changes after review
@@ -17,10 +24,13 @@ This changelog is generated by `changelog.py` using manually added semantic vers
  * Fixes some precision a few places
 Breaking change in `belt_length();` now requires a type argument
 
+#### [v14.1.1](https://github.com/nophead/NopSCADlib/releases/tag/v14.1.1 "show release") Fixes [...](https://github.com/nophead/NopSCADlib/compare/v14.1.0...v14.1.1 "diff with v14.1.0")
 *   2021-03-13 [`4b93623`](https://github.com/nophead/NopSCADlib/commit/4b93623492a2b8a073ab9dccc91fb2b21c475f21 "show commit") [C.P.](# "Chris Palmer") `changelog.py` now omits "Updated changelog" commits.
 
+### [v14.1.0](https://github.com/nophead/NopSCADlib/releases/tag/v14.1.0 "show release") Additions [...](https://github.com/nophead/NopSCADlib/compare/v14.0.1...v14.1.0 "diff with v14.0.1")
 *   2021-03-13 [`544e69c`](https://github.com/nophead/NopSCADlib/commit/544e69c71b404636df320be278b3fa7442f10429 "show commit") [C.P.](# "Chris Palmer") `pulley_pr()` now has an optional belt type for non-standard belt over smooth pulleys.
 
+#### [v14.0.1](https://github.com/nophead/NopSCADlib/releases/tag/v14.0.1 "show release") Fixes [...](https://github.com/nophead/NopSCADlib/compare/v14.0.0...v14.0.1 "diff with v14.0.0")
 *   2021-03-08 [`e46e6b6`](https://github.com/nophead/NopSCADlib/commit/e46e6b6e5b95792b5b2b4d7a7e4360beed22df0b "show commit") [C.P.](# "Chris Palmer") Fixed markdown numbered points in `core_xy`.
 
 ## [v14.0.0](https://github.com/nophead/NopSCADlib/releases/tag/v14.0.0 "show release") Breaking Changes [...](https://github.com/nophead/NopSCADlib/compare/v13.5.0...v14.0.0 "diff with v13.5.0")

docs/usage.md

@@ -1,7 +1,7 @@
 # NopSCADlib usage
 
 ## Requirements
-1. OpenSCAD 2019.05 or later, download it from here: https://www.openscad.org/downloads.html
+1. OpenSCAD 2021.01 or later, download it from here: https://www.openscad.org/downloads.html
 1. Python 2.7+ or 3.6+ from https://www.python.org/downloads/
 1. ImageMagick 7 www.imagemagick.org