v2.5.0

Introduce reward changes

At block 1'619'997 chain forks and per block dev reward is removed, with a once off dev payment of 100'000'000 NLG paid into address GSTG9pQ6yRdGurmjUDGwm8FyYc272vP13b

To keep the eventual supply at exactly 700'000'000 other small changes are then made:
* First halving is brought forward to block 2'074'989
* We slightly alter the rounding of each halving step to give cleaner numbers
* We continue halving for more rounds all the way down to 0.00000001 reward
* Final reward amount continues until block 433'009'989 with the 12.2709 NLG for this period being slowly paid out over a very very long period

Halving schedule as follows (every four years):
5 mining, 7.5 witness
2 mining, 4 witness
1 mining, 2 witness
0.5 mining, 1 witness
0.2 mining, 0.5 witness
0.1 mining, 0.2 witness
0.05 mining, 0.1 witness
0.02 mining, 0.05 witness
0.01 mining, 0.02 witness
0.005 mining, 0.01 witness
0.002 mining, 0.005 witness
0.001 mining, 0.002 witness
0.0005 mining, 0.001 witness
0.0002 mining, 0.0005 witness
0.0001 mining, 0.0002 witness
0.00005 mining, 0.0001 witness
0.00002 mining, 0.00005 witness
0.00001 mining, 0.00002 witness
0.000005 mining, 0.00001 witness
0.000002 mining, 0.000005 witness
0.000001 mining, 0.000002 witness
0.0000005 mining, 0.000001 witness
0.0000002 mining, 0.0000005 witness
0.0000001 mining, 0.0000002 witness
0.00000005 mining, 0.0000001 witness
0.00000002 mining, 0.00000005 witness
0.00000001 mining, 0.00000002 witness (Stays here until completion - block 433'009'989)