Small meta cleanups (#4893)

* Remove the unneeded pytest options from pyproject.toml

* Clean up setup.py from old readthedocs.org workaround

* Removes unused folder

* Simplify list of excluded files in black's configuration

* Fix returned exit codes in `make.ps1`

* Add Sublime's project files to `.gitignore`

* Update the link to Black in README and contributing guidelines

make.ps1

@@ -46,10 +46,12 @@ function reformat() {
 
 function stylecheck() {
     & $script:venvPython -m black --check $PSScriptRoot
+    Exit $LASTEXITCODE
 }
 
 function stylediff() {
     & $script:venvPython -m black --check --diff $PSScriptRoot
+    Exit $LASTEXITCODE
 }
 
 function newenv() {