BTREEFORMAT

Implementation of a btree based merkle tree.  The original merkle tree would not scale out to a large number of keys due to the limitation of keeping the tree in main memory.  Therefore we will try and store the 

btree file:
file header: version:1, blocksize:32, freepointer:64, rootpointer:64,
freekeys1:64, freekeys2:64, freekeys3:64, freekeys4:64, freekeys5:64
reserved/bytes:
header size: 85

node:{0,m:32,[keyhash:32],[childhash:32,child:64]}

leaf:{1,m:32,[keyhash:32,keypointer:64,valhash:32]}

freenode:{2,nextpointer:64,0:(blocksize-9)}

for nodes:
blocksize = 1 + 4 + D*4 + (D+1)*12
D = (blocksize-17)/16

for leaves:
blocksize = 5 + D*16
D = (blocksize-5)/16

65521



key file:

[key\0,key\0,key\0]

keys allocation

l = 2**4

m = 2**64



header size = 85 + (√blocksize - 4)*8