Add courses / challenge mode

[itszn]

This pull request will add support for courses and challenge sets. This allows a set of charts to be played in order with certain constraints and requirements.

• Read in / parse json challenge files (see https://gist.github.com/itszn/5c798ca96bc65043405a9eb9473328cb)
• Add challenge to database
• Parse .kco files
• Add challenge select screen
• Add challenge sorting
• Add challenge filtering
• Add challenge search
• Add GUI for challenge results
• Save results in database (separate hash based entry?)
• Add song settings to challenge select
• Add req text and text scrolling
• Support name + level
• Add docs

[itszn]

After some review, a few changes to be made:

• Move ChallengeIndex methods out of MapDatabase.cpp
• Try and shrink the generate description function
• Make challenge results scroll
• Add option for sdvx like completion %
• Add function to get challenge json from lua
• Remove macros from ChallengeSelect.hpp?
• Add Challenge score table and index by hash?