narrowspec: use sparse.parseconfig() to parse narrowspec file (BC)
This also make narrow files use 'include' and 'exclude' instead of plural forms
which are 'includes' and 'excludes'.
This is BC because existing narrowspecs have to replace excludes, includes words
with exclude and include i.e. their singular versions.
Differential Revision: https://phab.mercurial-scm.org/D4057
{
// Enforcing
"eqeqeq" : true, // true: Require triple equals (===) for comparison
"forin" : true, // true: Require filtering for..in loops with obj.hasOwnProperty()
"freeze" : true, // true: prohibits overwriting prototypes of native objects such as Array, Date etc.
"nonbsp" : true, // true: Prohibit "non-breaking whitespace" characters.
"undef" : true, // true: Require all non-global variables to be declared (prevents global leaks)
// Environments
"browser" : true // Web Browser (window, document, etc)
}