Instead of relying on local functions to inspect the classpath, use the
more robust, extensible versions in org.clojure/java.classpath.

See also http://dev.clojure.org/jira/browse/CLASSPATH-5

Affects these namespaces:

- clojure.tools.namespace.dependency
- clojure.tools.namespace.parse
- clojure.tools.namespace.track

With minor changes, these files are platform-neutral.

c.t.n.dependency is a general-purpose library which has many
applications outside of tools.namespace.

The uses for c.t.n.parse and c.t.n.track in ClojureScript are less
apparent, but they are easy to port. Perhaps by porting other namespaces
it will be possible in the future to have a version of c.t.n.repl that
works on non-JVM platforms.

Use tools.reader for platform-independent read.

Instead of clojure.core/read

This is trivial to write and is specific to the implementation of
`clojure-file?` and `clojurescript-file?`

Since a `nil` value for `read-opts` may be passed in by another function
such as c.t.n.file/read-file-ns-decl.

This reverts commit 60f6209.

Need this to be public to use in c.t.n.find for different platforms.

To be used in c.t.n.find

Rename 'clojure-platform' to 'clj' and 'clojurescript-platform' to
'cljs'.

Add docs and metadata for versions added/deprecated.

Deprecate 'scan' and 'scan-all', replace with 'scan-dirs' and
'scan-files' taking optional argument for clj/cljs platform.

Replaces deprecated dir/scan and dir/scan-all.

No reason for these not to be public, and it may be useful for
inspection from the REPL.

And add change log entries for 0.3.0

And clojurescript-read-opts to cljs-read-opts