This pull request updates RegTest network settings to the same settings I used in my recent video where I demonstrated a fix for the DGB mining reward decay to go to 0 instead of 1. Also in this pull request, I provide the 1-line fix to make sure the reward goes to 0 and does not stay at 1 infinitely.

Here is a link to the video where I demo the test & prove this fix: https://www.youtube.com/watch?v=BcOOxoHXJ0I

The main issue is caused by 1 line of code:
if (nSubsidy < COIN) { nSubsidy = COIN; }

Simply needs to be changed to:

if (nSubsidy < COIN) { nSubsidy = o; }

In addition to the regest changes I also changed a few more variables locally to speed up the previous DGB hardfork points. These local changes if anyone wants to test themselves were below, bottom line of each was test change to make network simulate changes faster with regtest mining. Note the below changes are not in this PR, this is just for reference.

if  (nHeight < 1440)
if (nHeight < 3)

else if (nHeight < 5760)
else if (nHeight < 6)

int64_t months = blocks * BLOCK_TIME_SECONDS / SECONDS_PER_MONTH;
int64_t months = blocks * 1;```