v6.0.0 notes, build machinery changes

.travis/Brewfile

@@ -6,6 +6,7 @@ brew 'leptonica'
 brew 'libffi'
 brew 'libtiff'
 brew 'libxml2'
+brew 'mupdf-tools'
 brew 'openjpeg'
 brew 'qpdf'
 brew 'tesseract'

.travis/autobrew.py

@@ -15,6 +15,7 @@ class Ocrmypdf < Formula
   ${ocrmypdf_sha256}
 
   depends_on "pkg-config" => :build
+  depends_on "mupdf-tools" => :build  # statically links libmupdf.a
   depends_on "freetype"
   depends_on "ghostscript"
   depends_on "jpeg"

docs/release_notes.rst

@@ -5,6 +5,20 @@ OCRmyPDF uses `semantic versioning <http://semver.org/>`_ for its command line i
 
 The OCRmyPDF package itself does not contain a public API, although it is fairly stable and breaking changes are usually timed with a major release. A future release will clearly define the stable public API.
 
+v6.0.0
+------
+
+-   The software license has been changed to GPLv3. The license of test files 
+
+-   OCRmyPDF now depends on `PyMuPDF <https://pymupdf.readthedocs.io/en/latest/installation/>`_. Including PyMuPDF is the primary reason for the change to GPLv3.
+
+-   Fixed an issue where OCRmyPDF failed to detect existing text on pages, depending on how the text and fonts were stored within the PDF. (#233, #232)
+
+-   Fixed an issue that caused dramatic inflation of file sizes when ``--skip-text --output-type pdf`` was used. OCRmyPDF now removes duplicate resources such as fonts, images and other objects that it generates. (#237)
+
+-   Improved performance of the inital page splitting step. Originally this step was not believed to be expensive and ran in a process. Large file testing revealed it to be a bottleneck, so it is now parallelized. (#234)
+
+
 v5.7.0
 ------