libdreamcast split

[skmp]

Following up on monday's meeting

Proposal:

• Split is after r8 release. We need to decide on a day. How about next monday?
• We'll convert makefiles to CMake
• Everything under core/ will be moved to the libdc/ folder
• Everything under shell/ will be moved to reicast/
• There is little change to our CI/CD flows (just fixing up the build scripts)

Notes:

• It would be best to have as much mature work merged to core/ by the split date. After that, we'll have to cherry pick.
• People working in lower level / core should rebase to the new project structure as soon as possible after the changes, to avoid ugly merges

[skmp]

After discussing w/ @dmiller423, there's the counter proposal to keep everything in a fat repo, rename core/ to libdreamcast/ and shell/ to reicast/. This way we don't have to re-do work for CI, or further complicate our repo structure.

[skmp]

@dmiller423 updated the ticket. Better now?

[dmiller423]

[ As a branch until complete ]

[skmp]

Yeh yeh

[skmp]

Alright, r8 is out. Let's start work on this!