support config files in .ini style format

[gdamjan]

cgit currently uses it's own style of config files. there's value of making it support the git (more or less .ini) format of config files. And since it already bundles/links git, the git config api can be used.

One immidiate use case is a single config file hosting of cgit with uwsgi + cgi. For example:

#! /bin/sh

exec /usr/bin/uwsgi --ini $0

[uwsgi]
master          = true
http-socket     = :8000
offload-threads = 5
async           = 1000
ugreen          = true
plugin          = 0:cgi
cgi             = /=/usr/lib/cgit/cgit.cgi
check-static    = /usr/share/webapps/cgit/
env = CGIT_GIT_CONFIG_FILE=%p

[cgit]
branch-sort=age
enable-commit-graph=1
enable-index-links=1
enable-git-config=1
scan-path=.

[gdamjan]

consider the section= concept in cgit config files, and maybe replace it with [cgit "section-name"] which should be supported by the git config api.