Merge Novel Layouts (#837)

* Merge novel layouts and simplify the Tokenizer class
* Fix core tests
* Delete auto-layout code
* Remove no longer needed item layouts
* Remove references to deleted item layouts in test
* Make some minor changes to Tokenizer class and update tests
* Update test reference files
* Update sample project
* Fix a few issues with the Tokenizer
* Centre some text in the sample documents
* Make some minor changes to how new projects are generated
* Add support for New Page and VSpace commands to the Tokenizer
* Remove Title and Page layouts and add codes for page break and vertical space
* Add document layout and fix some issues in index class with new title formats
* Update tests and reference files
* Bump the project file version and fix a minor issue in items class
* Update tests and test coverage
* Clean up some warnings and issues in tests

tests/minimal/content/8c659a11cd429.nwd

@@ -1,5 +1,5 @@
 %%~name: New Scene
 %%~path: a6d311a93600a/8c659a11cd429
-%%~kind: NOVEL/SCENE
+%%~kind: NOVEL/DOCUMENT
 ### New Scene
 

tests/minimal/content/a35baf2e93843.nwd

@@ -1,6 +1,6 @@
 %%~name: Title Page
 %%~path: a508bb932959c/a35baf2e93843
-%%~kind: NOVEL/TITLE
-# Minimal
+%%~kind: NOVEL/DOCUMENT
+#! Minimal
 
-By Jane Doe, John Doh
+>> By Jane Doe, John Doh <<

tests/minimal/content/f5ab3e30151e1.nwd

@@ -1,5 +1,5 @@
 %%~name: New Chapter
 %%~path: a6d311a93600a/f5ab3e30151e1
-%%~kind: NOVEL/CHAPTER
+%%~kind: NOVEL/DOCUMENT
 ## New Chapter