Fixed compile on macOS

Since Guichan is currently disabled on Homebrew, I've opted for adding
it as a submodule instead. It currently references the 0.8 branch of
Guichan, after I cherry-picked the CMake support from the master
branch.

When using SDL2 installed through Homebrew, it was necessary to use
SDL2_LINK_LIBRARIES, since the libraries occupy various different
directories.

It no longer seems necessary to include an SDLMain.m, so I deleted it.

Removed obsolete OS X instructions.

Also added instructions for installing dependencies on Fedora.

Removed mentioning of /announce and /who in the README, since they were
removed for tmwAthena.

1 files changed, 0 insertions, 0 deletions

diff --git a/libs/guichan b/libs/guichan
new file mode 160000
+Subproject 94914a027276b8f60a028717bcbea4e674298c2