terminal.js:  Fixed a bug where `GateOne.Terminal.highlight()` would leave leftover/unused ``<span>`` elements everywhere after you called `GateOne.Terminal.unHighlight()`.
terminal_input.js:  Added an extra check to `GateOne.Terminal.Input.capture()` and `GateOne.Terminal.Input.disableCapture()` to prevent duplicate functions being added via `addEventLlistener()`.  I don't think it was a problem but it's more efficient this way (in case someone calls `capture()` more than once without ever calling `disableCapture()`).
Bookmarks plugin:  Adjusted/optimized the CSS a bit.
Bookmarks plugin:  Fixed a bug where you'd get an exception trying to import bookmarks when using Python 3.
Bookmarks plugin:  The initial bookmarks sync is now attached to the `go:js_loaded` event instead of the `go:user_login` event.  This should make it more reliable (since the `Bookmarks.init()` function could often be called *after* the `go:user_login` event had fired).
termio.py:  If you pass an `env` dict to `Multiplex.spawn()` that happens to have a `$TERM` value set it will be preseved when spawning the process.
termio.py:  A bit of code optimization/cleanup.
app_terminal.py:  Added support for adding "environment_vars" to your 50terminal.conf to set any default environment variables you want before terminal applications are spawned.  Also added a reasonable default (with a `$TERM` value) for when a new 50terminal.conf is generated (e.g. first-run situation).