[Qt] move SubstituteFonts() above ToolTipToRichTextFilter

- doesn't belong to the ToolTipToRichTextFilter class so move it up
bitcoin-tx: fix build warnings

Cleans up a bunch of:
warning: missing braces around initializer for ‘const<anonymous struct>’
Merge pull request #4696

616c243 bitcoin-tx: fix build warnings (Cory Fields)
Merge pull request #4659

c4bae53 [Qt] move SubstituteFonts() above ToolTipToRichTextFilter (Philip Kaufmann)
Closely track mempool byte total. Add "getmempoolinfo" RPC.

Goal:  Gain live insight into the mempool.  Groundwork for future work
that caps mempool size.
build: fix automake warnings about the use of INCLUDES

While we're at it, reduce the use of LIBS as well. This makes dependencies
explicit.

Fixes building with (the not-yet-merged) libsecp256k1 as well.

Github-Pull: #4689
Rebased-By: Wladimir J. van der laan <laanwj@gmail.com>
Rebased-From: 909b347 c0e5dda
Merge pull request #4638

6f2c26a Closely track mempool byte total. Add "getmempoolinfo" RPC. (Jeff Garzik)