use remove-from-invisibility-spec

Use `remove-from-invisibility-spec' instead of the compatibility wrapper
`org-remove-from-invisibility-spec'.  The former exists for a long time
now and we are already using `add-to-invisibility-spec' anyway.
declare variables right after require forms
defer loading org

Instead of requiring `org' when `orglink' is loaded, defer doing so
until `orglink-mode' is called.  Loading `org' takes a long time.

Add a kludge to `turn-on-orglink-mode-if-desired' to prevent
`orglink-mode' from being activated in the *scratch* buffer.  If
we didn't do that then `org' would be loaded at startup anyway.

Also declare some functions and variables to quiet the byte-compiler.
bump to 0.2.0

Actually remove the Version library header.  That's what tags are for.

While we are at it also remove the Status header.  This package is
working well enough not to require the "beta" stigmata anymore.