stability improvement

corrects a memory leak which may cause ccminer after a long while if the ressources (ram/virtual memory) are limited.

Procedure for solo mining.

wallet side
edit or create the file zcoin.conf and add these informations to allow mining (this is an example):
server=1
rpcuser=djm34
rpcpassword=password
rpcport=8382
rpcallowip=127.0.0.1 (if the IP address of the miner is the same as the one of the wallet), otherwise it should be the address of the miner)

in the miner command line:
ccminer -a mtp -o http://127.0.0.1:8382/ -u djm34 -p password --coinbase-addr zcoin_address --no-getwork --no-stratum

In the case of the wallet is on a different machine http:// should point to the IP of the machine where the wallet is located and in the wallet config, rpcallowip to the address of machine where the miner is located

The address given in --coinbase-addr, does not need to be an address of the wallet to which the miner is connected any zcoin address should work.