Remove the mandatory "per-dust-output" fee rule.

Instead, enforce a rule similar to Bitcoin:  Completely disallow (no
matter what fee) outputs less than 0.001 NMC.
Enforce a minimum name coin amount.

Introduce a softfork that enforces a minimum amount of locked coins for
each (newly updated) name.
Reject tx with too low fee from mempool also before fork.

For inclusion into mempool and newly mined blocks, reject name
transactions with too little locked coins even before the fork point.
Merge pull request #201 from domob1812/txfees

Remove the mandatory "per-dust-output" fee rule.
Merge pull request #205 from domob1812/enforced-fee

Enforce locked name coin amount.
Clean up name_new a bit.
Replace FORK_HEIGHT_TXVERSION with FORK_HEIGHT_STRICTCHECKS.