Not abandoned. I'm still working on it, albeit more slowly than before
I pushed out an updated a few weeks ago, but there were some new bugs introduced so I had to halt the rollout. I'm still trying to sort out what the problem is, once I do I'll push out a fixed version
You can check the Github commits for a more accurate picture on how actively I'm working on the app: https://github.com/moezbhatti/qksms/commits/master
Get the app "Join" if you're using Chrome as your desktop web browser, otherwise Pushbullet for other browsers. Either will let you text from your PC while still using Qksms as your default messaging app.