[version 5.2.69] (#45)

Co-authored-by: Escanor Liones <[email protected]>

Define and implement hard diff removal hardfork (#41)

* Bump to version 5.1.42 & setup BIP9 deployment for hard diff removal

* CalculateNextWorkRequired: Implement hard diff removal hardfork

* CalculateDifficultyDelta: Fix comment and adjust difficulty faster when the block time outside of 15 ~ 60 minutes range

* CTestNetParams: Adjust DEPLOYMENT_HARD_DIFF_REMOVAL conditions

* getblockchaininfo: Show hard_diff_removal status

[version] Update version number.

Merge branch 'release_5.0.69'

[RELEASE] v4.23.69

[RELEASE] 4.22.69

[RELEASE] Mark release.

Merge pull request #15 from FACT0RN/chore/releaseflag

mark as release