9952616 [Trivial] Update copyright headers for 4.0.2 (Fuzzbawls)

Pull request description:

  Updates copyright headers to reflect file changes in the year 2020 so far.

  scripted change using the `contrib/devtools/copyright_header.py` script.

  Also updates the copyright year in `COPYING` and `configure.ac` to 2020

ACKs for top commit:
  random-zebra:
    utACK 9952616
  furszy:
    utACK 9952616

Tree-SHA512: 843b6b116ca8bb1208e332def726eba066dc26c289622d8b51c0c0ebe1da9464f6f7b553c0b4dfa7d94ee89cca8f6f3ef3883cff972c39bc3d68ee6da1f77d05

Github-Pull: PIVX-Project#1272
Rebased-From: 9952616

4663310 [GUI] Min window size (furszy)
5c76d51 Doc: Update manpages for 4.0.2 (Fuzzbawls)
79bfec9 Build: Bump version to 4.0.2 (Fuzzbawls)
82d0af7 Doc: Update release notes for 4.0.2 (Fuzzbawls)
3432e29 [GUI] Transaction record cold staking fixes. (furszy)
e5badbc [RPC] Don't do extra PoW round for pos blocks in 'generate' RPC Github-Pull: #1274 Rebased-From: 6b5ce00 (random-zebra)
7b8169c [Trivial] Update copyright headers for 4.0.2 (Fuzzbawls)
8faf4bf [Core] Update checkpoints for first v7 block (Fuzzbawls)
f6e8a14 [GUI] Add latest block number to topbar pushButtonSync Github-Pull: #1268 Rebased-From: 84b4ae4 (random-zebra)
8edfa83 [GUI] Connect P2CSUnlockOwner and P2CSUnlockStaker records to the model Github-Pull: #1265 Rebased-From: 4b24380 (random-zebra)
e475827 [GUI] CoinControlDialog, removing extra spacing char from the copy to clipboard texts. (furszy)
dbe2b3a [GUI] CoinControlDialog, copy to clipboard action implemented on every showed label + inform snackbar notifying the user. (furszy)
3404bd9 [Wallet] Don't add P2CS automatically to CWalletTx::GetLockedCredit Github-Pull: #1264 Rebased-From: 4789652 (random-zebra)
d1f5731 [GUI] Force NavMenu to show dashboard button at startup. (furszy)
cdee261 [GUI] Open the app's window in the smallest, currently available, size. (furszy)
fc766c8 [GUI] TransactionRecord type P2CSDelegationSentOwner and P2CSDelegationSent distinction. (furszy)
49de2e4 [Qt][Bug] Load the most recent instead of the first transactions (Fuzzbawls)
827ca3e [Bug][GUI] Double counted delegated balance fix. (furszy)

Pull request description:

  Updates the `4.0` branch with relevant merged PRs in preparation for tagging the `4.0.2` release.

  Included PRs:
  #1261
  #1267
  #1263
  #1266
  #1264
  #1269
  #1265
  #1268
  #1273
  #1272
  #1274
  #1279

Top commit has no ACKs.

Tree-SHA512: 561d9319d08756c040751c6ce145505610ed2ebc4351a87d9d3bb05ecb98df9f35d492e9e3eb7e111ce611268c4a24bb13720e3f81917a671038f8ab23f14de4