Add documentation.

Author: stevecheckoway

.gitignore

@@ -3,4 +3,9 @@
 *.fls
 *.synctex.gz
 *.log
+*.idx
+*.ilg
+*.ind
+*.out
 test.pdf
+/doc/tikzlibraryspline.pdf

CHANGELOG.md

@@ -0,0 +1,18 @@
+# Changelog
+All notable changes to this project will be documented in this file.
+
+The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/)
+and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.html).
+
+## [Unreleased]
+
+## [1.0.0] - 2018-03-13
+### Added
+- `spline through` style
+- `closed spline through` style
+- `spline coordinates` option
+- `spline debug` option
+- Documentation
+- Public domain `control_points.py` code
+- LICENSE
+- CHANGELOG.md