Update xlib.nim

remove -d:MACROS requirement for xlib shortcut functions
Update xutil.nim
Update glx.nim

glx attributes should be int32
Update xutil.nim

removed converter
Update keysym.nim

properly type all the keysyms
Add DragonFly as essentially a clone of FreeBSD
Exposed process file handles in osproc module.

The file handles of a PProcess instance can now be accessed through
the inputHandle(), outputHandle(), and errorHandle() methods.

Also tidied up documentation for stream accessor procs a bit.
Added a TSocketHandle type to winlean.nim and posix.nim

Edited sockets.nim and asyncio.nim to use the new TSocketHandle type.
Merge pull request #624 from Varriount/win64/fix-sockets

Added a TSocketHandle type to winlean.nim and posix.nim
Merge pull request #622 from rbehrends/master

Exposed process file handles in osproc module.
Merge pull request #615 from fowlmouth/patch-10

Update xlib.nim
Merge pull request #617 from markuspf/master

Add DragonFly as essentially a clone of FreeBSD