Test all features

Add cases for attribute highlight on and off, block syntax by lang
and emmet-vim group names, OnChangeVueSyntax(), matchit, .wpy,
initial_indent as syntax and tag.syntax, and syntax after reloading.

Also check indenting a file after removing all indent with
g:test_flatten, which fails before the end tag fix as closing tags at
column 0 were taken as block end tags.

README.md

@@ -217,7 +217,14 @@ Run tests with Vim and Neovim, whichever is installed
 ./test/run.sh basic template  # Only these cases
 ```
 
-Each case is a `.vue` file in [test/cases](test/cases), with an optional `.vim` file for the config and syntax checks. A case fails if indenting the whole file changes it, a check fails, or there is an error message. Tests also run on GitHub Actions for each push and pull request.
+Each case is a `.vue` or `.wpy` file in [test/cases](test/cases), with an optional `.vim` file for the config and checks. A case fails if
+
+- indenting the whole file changes it
+- with `g:test_flatten`, indenting the file after removing all indent doesn't restore it
+- a check in `Check()` fails, such as syntax, `GetVueTag()`, `GetVueSyntax()` or fold level
+- there is an error message
+
+Tests also run on GitHub Actions for each push and pull request.
 
 ## Acknowledgments & Refs