Chunked resends are now sent "on-demand" instead of all-at-once

When MaxMessagesInResendRequest is set, QuickFIX generates multiple
"chunked" resends - and all of them at once. The CME rejects the second
resend complaining that a resend is already in progress (the first).

Modified the resend logic to send the next chunk only when the first one
is complete (i.e. when the last seqnum of the first has been received).
Fixed field namespace bug
Corrected acceptance test for MaxMessagesInResend for delayed chunking
Merge branch 'resend_chunking' of github.com:roji/quickfixn into chunked_resend_153

Conflicts:
	QuickFIXn/ResendRange.cs
issue #153 - restore ctor, deprecate another
credit for #153
Merge branch 'master' into chunked_resend_153

Conflicts:
	NEXT_VERSION.md
Merge pull request #194 from connamara/chunked_resend_153

153 upmerge plus minor interface restoration