RILEYS REVENGE (2.3.2) - Pinkcoin Maintenance Development

Author: RP

It's time for a little maintenance in the Pinkcoin engine room.

This page will be updated periodically so be sure to check in for updates.

The source repository at https://github.com/Pink2Dev/Pink2 needs some minor updating that would lead to an eventual maintenance release (2.3.2) that would have to be approved by the official team.

I have already completed some work in a separate git repository where progression can be viewed. Each commit will be PGP signed to verify it's authenticity.
Staging Repository:
https://github.com/opsinphark/Pink2

TESTING:
These commits are being tested on a full time node with an active internet connection. Participants are encouraged in this process to produce the best possible result.

TRACKING
You can check/view the progress here at the GitHub repository.
https://github.com/opsinphark/Pink2/projects/1
https://github.com/opsinphark/Pink2/commits/next-dev

REPORTING:
If there are any issues or something you wish to see addressed please report them using the GitHub issue tracker on the staging repository located here:
https://github.com/opsinphark/Pink2/issues

COMPLETED:
- build: Fix compatibility issue with boost version 1.66+.
* Allows source code to compile on modern systems.

- consensus: Remove unused 'nBestInvalidTrust` state.
* Completely unused, resource expensive under certain conditions.

- net: Change 'MAX_OUTBOUND_CONNECTIONS' default to 12 from 64.
* The higher number of connections the more resource expensive the node becomes, this is not desired by default or on platforms such as RaspberryPi or similar. This behavior can be changed by adding 'maxconnections=64' to the .conf file.

- build: Increment version to 2.3.1.88, 'PROTOCOL_VERSION' to 60019 and 'CLIENT_VERSION_SUFFIX' to 'Rileys Revenge'
* Makes the node distinguishable until proper versioning can be provisioned from the official team.
Yes, we've gone semi-rogue here.

- net: Increment 'MIN_PEER_PROTO_VERSION' to 60018 (2.3.1 Riley)
* Drops connections with protocol versions less than 60018 2.3.1 (Riley)
* 2.3.1 (Riley) was the mandatory update that forked to pure proof of stake. Connecting with anything less is not necessary.

- build: Fix compatibility issues with dependency OpenSSL 1.1.x
* This was already done with minor issues in a PR on the original repository by @Scalextrx. This was pulled, edited for changes, squashed and committed.

- net: Make 'MAX_OUTBOUND_CONNECTIONS' configurable
* Introduces a new configurable switch: -maxoutboundconnections
Controls the maximum amount of outbound connections.
The hard coded default for `-maxoutboundconnections' is 12.
eg:
command line: pinkcoin-qt -maxoutboundconnections=24
.conf: maxoutboundconnections=24

TO DO/IN PROGRESS:
- crypto: Implement modern scrypt algorithm
- gui: Pull in changes from @astrych for the Qt BTC price API
- gui: Implement Qt DPI scaling support (4k monitor support)
- build: Fix compatibility issue with Alpine Linux
- docs: Update build instructions for dependency changes
- docs: Update example .conf file with new configuration switch
- docs: Update README.md
- regression testing