Makefile Update

Brought the Linux makefiles up to date with the Windows makefiles.

Added a rule to data.mk download allkeys.txt from unicode.org if it's not present in the UCA folder.

Broke the cleanup rules out better, moving data-related cleanup into data.mk.
Merge branch 'master' into linux
Merge branch 'master' into linux
.gitignore

Using the Komodo Edit text editor on Linux.  Added entries to .gitignore to ignore the files/folders that it creates.
Linux Makefile Update

Brought the Linux makefiles up-to-date with the Windows makefiles.
Clang

Compiler on Linux is now Clang rather than GCC.
Merge branch 'linux'

Linux and Windows support has been equalized.