Automatic Style Creation by adding .SLD file to GEOSERVER_DATA_DIR/styles

cutting/pasting from an email thread (which CHolmes subsequently said to greate a Jira issue for):

unlike FeatureTypes, styles are styles, there's no metadata. the only
thing that notates the fact that a given style exists is one entry in
the catalog.xml file, where the name of the style is ALWAYS the name of
the SLD file, sans .sld prefix. as such, i think that when a .sld file
exists in the styles directory, it should automatically be taken to
exist as a usable style.

my thinking comes from my current hacked up and awkward but beautiful
use of GeoServer to create real dynamic data maps (eg:
http://transit.frumin.net/trx/maps/subway-orig.png). In order to create
lots of different GIS queries, one needs to create a lot of SLD files
with different sets of rules/ranges/etc. having to always go into the
GeoServer admin to add a style is untenable.

note: it is possible to programatically add a featuretype/layer at this
point, by adding to the featureTypes directory. but not so with styles,
w/out also adding the extra-silly <styles> area of the catalog.xml file,
and can't really be done atomically if the running app is also
using/editing that file.