Support for some form of live reload

[almarklein]

Like running flexx serve, and upon saving the file that defines your app, it gets automatically reloaded in the browser, preferably with state (i.e. what tab is open) preserved.

[almarklein]

Looked into this for a bit. The main bottleneck seems to be a proper (cross platform) solution to watch the file system. I guess we may have an optional dependency for this functionality though.

[almarklein]

Quoting @Korijn:

During development, especially when styling, an auto-reload feature for at least the webruntimes would be a nice boost for productivity.

Tornado offers this: http://www.tornadoweb.org/en/stable/autoreload.html
Alternatively you can use watchdog to implement something similar: https://pypi.python.org/pypi/watchdog