Github-Pull: bitcoin#2305
Rebased-From: f8764b9

Each FAQ answer content is formatted as a self-contained HTML page for
styling purposes, however, having raw HTML in the `.ui` file's
`<string>` properties means that said HTML tags are also exported to
Transifex. This leads to a very ugly and confusing translation
experience that is prone to errors.

Here, we split up the content into shorter HTML-less strings: each list
item is it's own string, and each paragraph is it's own string. No HTML
tags are exported to Transifex.

The necessary HTML tags are added by way of helper functions that wrap
each string programmatically.

Github-Pull: bitcoin#2260
Rebased-From: ea7f593

Github-Pull: bitcoin#2348
Rebased-From: a55f2d0

Github-Pull: bitcoin#2350
Rebased-From: 4f90a19

Github-Pull: bitcoin#2353
Rebased-From: 274fb26

on macOS:
listSnapshot was leaking in findStartupItemInList()
bitcoinAppUrl was leaking in [Get|Set]StartOnSystemStartup()

Github-Pull: bitcoin#2374
Rebased-From: 5c07620

-BEGIN VERIFY SCRIPT-
sed -i 's/\<NULL\>/nullptr/g' src/qt/guiutil.cpp
-END VERIFY SCRIPT-
Github-Pull: bitcoin#2374
Rebased-From: aad1362

The problem arises when we trigger the balance update worker task and the chain tip changes (due a reorg) before one of the threadpool's threads start executing the update task. As the tip in this situation has the same height that the one cached inside the model, the `processBalanceChangeInternal` returns true without setting the processing flag to false again. Blocking every future balance update.

Github-Pull: bitcoin#2379
Rebased-From: fbda4d2

Github-Pull: bitcoin#2384
Rebased-From: fc6d7b9

coming from btc@05242e937d3fc0144029ccf3b14f98662400dd60

refs bitcoin#8225

To ensure the GUI closes when the "Minimize on close" window option is disabled, and the "Minimize to the tray instead of the taskbar" window option is enbaled, remove a check made against the "Minimize to the tray instead of the taskbar" value, made during GUI closure.

To ensure the GUI minimizes to the taskbar when the "Minimize on close" window option is enabled, and the "Minimize to the tray instead of the taskbar" window option is disabled, minimize the GUI and ignore the closure event.

Github-Pull: bitcoin#2377
Rebased-From: d72f7b5

… being banned.

Moved TRY_LOCK to LOCK to perform the budget maps check every 14 blocks without exception. If peers doesn't perform the validation and update proposals, votes and budget finalization maps at the same network time, then there could be a peer sending votes that aren't longer valid and end up being banned.

Github-Pull: bitcoin#2395
Rebased-From: 7faa5e9

Github-Pull: bitcoin#2401
Rebased-From: b02f0ab

Github-Pull: bitcoin#2401
Rebased-From: 139707b

…and will be removed on September 20, 2021.

Moved cmake workflow using Ubuntu 16.04 to Ubuntu 18.04.

Github-Pull: bitcoin#2413
Rebased-From: f3fe9b3