[svn] * src/lock.h,src/lock.c,src/noffle.c: Add lazy lock release. Only release the lock and close the databases if (a) another process signals us SIGUSR1 indicating it wants the lock, or (b) it is explicitly requested by a call to new function Lock_syncDatabases(). When waiting for the lock, SIGUSR1 the holding process every second. This is all an attempt to minimise the number of times we need to close and open the database. When (ha!) the database is replaced by something that can handle multiple simultaneous writers (with appropriate locking) this won't be necessary.