HAProxy syntax support in Atom

Adds syntax highlighting to HAProxy configuration files in Atom. Based on now unavailable HAProxy.tmbundle.

Syntax highlighting is partially auto-generated with script generate.py. This script parses configuration.txt from haproxy.org and generates haproxy.cson from haproxy.cson.template.

Updating grammars

Manual update

Update grammars/haproxy.cson. When done, make same changes in haproxy.cson.template, which is used for generating grammars from HAProxy docs.

Updating from docs

Make changes in haproxy.cson.template or (in case of new HAProxy release) provide new HAProxy docs. Download HAProxy configuration.txt for latest stable version from haproxy.org, and run python3 ./generate.py -d path/to/configuration.txt --out grammars/haproxy.cson.