use build and twine to publish source and wheel

Signed-off-by: Qijia Liu <[email protected]>

.gitignore

@@ -24,6 +24,8 @@ user.build.properties
 __pycache__/
 *.py[cod]
 *$py.class
+# Build results
+*.egg-info/
 
 ## CSharp and VisualStudio, selected lines from https://raw.githubusercontent.com/github/gitignore/master/VisualStudio.gitignore
 # User-specific files

doc/releasing-antlr.md

@@ -338,7 +338,13 @@ Nuget packages are also accessible as artifacts of [AppVeyor builds](https://ci.
 
 ### Python
 
-The Python targets get deployed with `setup.py`. First, set up `~/.pypirc` with tight privileges:
+The Python targets get deployed with `setup.py` (Python 2), or `build` and `twine` (Python 3).
+Install them by
+```sh
+pip3 install build twine
+```
+
+First, set up `~/.pypirc` with tight privileges:
 
 ```bash
 beast:~ $ ls -l ~/.pypirc
@@ -368,12 +374,13 @@ cd ~/antlr/code/antlr4/runtime/Python2
 python setup.py sdist upload
 ```
 
-and do again for Python 3 target
+For Python 3 target, do
 
 ```bash
 cd ~/antlr/code/antlr4/runtime/Python3
+python3 -m build
 # assume you have ~/.pypirc set up
-python3 setup.py sdist upload
+twine upload dist/antlr4-python3-runtime-<version>.tar.gz dist/antlr4_python3_runtime-<version>-py3-none-any.whl
 ```
 
 There are links to the artifacts in [download.html](http://www.antlr.org/download.html) already.