Since which version is the mining functionality removed from the wallet? As I'm starting to learn to create a new altcoin, I found there is a remarkable difference between old and new Bitcoin/Litecoin Core wallet: old versions (0.6.9 of Litecoin) have mining functionality integrated in the wallet with a tab and a button for it while new versions (from 0.7.0.1 of Bitcoin) don't.
So my question is from which version is the mining functionality removed from the wallet? Are there any change logs/release notes/statements that tell about this change? And can someone tell me why we should separate it from the wallet?
I really want to see if I can re-integrate this functionality back to the wallet as most of my clients are low-tech and a button &quot;Mining&quot; will be definitely much visually easier then running bunch of lines of command in the terminal.
I guess some of you may then start to tell me to stop creating new altcoins but my clients really want to have a new bitcoin-like currency for their private business so I think you will unlikely to see it public elsewhere if you're not part of the business so never mind. :)
Any reference links or articles or kinds of help will be highly appreciated. Thank you!
Bitcoin Core removed it in version 0.13.0.  You can see the change log at https://bitcoin.org/en/release/v0.13.0:


  Removal of internal miner
  
  As CPU mining has been useless for a long time, the internal miner has been removed in this release, and replaced with a simpler implementation for the test framework.


For future questions like this, all change logs can be found at https://bitcoin.org/en/version-history.