Merge branch 'feature/improve-diff-view-styling' into t

Conflicts:
	libgitg/resources/diff-view-html-builder.js
	libgitg/resources/diff-view.css
	libgitg/resources/diff-view.html
Merge branch 'feature/improve-diff-view-styling' into t

Conflicts:
	libgitg/resources/diff-view.css
Merge branch 'feature/improve-diff-view-styling' into t

Conflicts:
	libgitg/resources/diff-view.css
Merge branch 'feature/separate-commit-message' into t

Conflicts:
	libgitg/resources/diff-view.css
	libgitg/resources/diff-view.html
Merge branch 'feature/separate-commit-message' into t

Conflicts:
	libgitg/resources/diff-view.css
	libgitg/resources/diff-view.html
	libgitg/resources/diff-view.js
Merge branch 'feature/keep-scrollbar-at-bottom' into t

Conflicts:
	libgitg/resources/diff-view.css
	libgitg/resources/diff-view.js
Merge branch 'feature/keep-scrollbar-at-bottom' into t

Conflicts:
	libgitg/resources/diff-view.css
	libgitg/resources/diff-view.js
Merge branch 'feature/keep-scrollbar-at-bottom' into t

Conflicts:
	libgitg/resources/diff-view.css
	libgitg/resources/diff-view.js
Merge branch 'feature/separate-commit-message' into t

Conflicts:
	libgitg/resources/diff-view.css
	libgitg/resources/diff-view.html
Show message body with the commit diff

Also make it scroll with the commit diff.