A rewrite of FTPiiU, an FTP server for WiiU homebrew

This started as an attempt to add a new feature to FTPiiU, but there's a number of problems with that codebase:

• It requires libogc, which is a Wii library
• Tons of compiler warnings
• Doesn't work when built with current tools

So, it became a rewrite of sorts:

1. I started with the Wii U bootstrap code from RetroArch
2. Created main() and built it out following FTPiiU as a guide, but
3. Applying my own design standards to it to improve code quality.

FTPservU is not yet functional as an FTP server.

• Compiles with no warnings
• Launches without DSI error / crash
• Welcome message displayed upon connection
• successfully parses out commands sent to the control connection
• successfully responses back to the control connection
• authentication commands implemented
• Passive transfer mode implemented
• Active transfer mode implemented
• Data commands implemented

You will need the following:

• devkitPPC r28 (r29 and r29-1 are untested and may break things)
• libfat and libiosuhax installed under portlibs

The directory structure ends up looking like this:

$DEVKITPRO (e.g. /opt/devkitpro)
|
+-$DEVKITPPC (typically devkitPPC)
|
+-portlibs
  |
  +-ppc
    |
    +-include
    |   fat.h
    |   iosuhax_devoptab.h
    |   iosuhax_disc_interface.h
    |   iosuhax.h
    |   libfatversion.h
    |
    +-lib
        libfat.a
        libiosuhax.a

Once you have the structure set up, building is simple:

1. Ensure DEVKITPRO and DEVKITPPC variables are set appropriately
2. run make all which will build both an ELF and an RPX.
3. Create the directory /wiiu/apps/FTPservU/ on your WiiU's SD card and drop the ELF or RPX into it (one or the other, not both!)

TODO: Script together a dist directory so that it can be unzipped onto the SD card and used by HBL easily.