Modify the source directory structure

Move all source files into a 'Src' directory, and move header files into
an 'Include' directory. Inside each of these sort files by their concern
(networking code in 'Network', OpenGL code in 'Gl', etc.) Update build
systems accordingly; however _remove_ systems that reference Solaris.

The project already prefixed files with character codes indicating their
use but when merging projects it would be favourable to have a more
focused list when looking at certain areas of the codebase.

All Visual Studio projects still attempt the compilation process
correctly. The makefiles designed for Linux have been modified but are
__untested__ due to inaccessiblity. Support for Solaris has been dropped
because of its Oracle association but source code for the platform
remains because it references the X Server.
Remove a collection of temporarily generated files

Remove files that are either not required, generated on demand during a
build, or created by Visual Studio when it is opened.

Such files are temporary, and change from access to access, build to
build; they do not need to be version tracked.
Correct name clash `errno` with name in 'errno.h'

Modify instances of the name `errno` found in the networking code to
`wsaerrno` to indicate use, and prevent name clashes with the value
found in 'errno.h'.

The local declaration `int errno` found in several functions across the
networking portion of the Quake code base clashes with the name that is
found in 'errno.h'. This clash is likely because of modifications of the
C standard library in more _recent_ iterations of compilers.

This modification corrects the compilation issue in __both__ Quake World
and WinQuake code bases.
Inform Visual Studio to ignore 'LIBC.lib'

Make use of the 'NODEFAULTLIB[:library]' flag for Visual Studio's linker
to ignore the library 'LIBC.lib' that several Quake projects _appear_ to
try an link to.

The Visual Studio tool-chain is unable to find this particular library
in order to complete compilation. However, __brief__ testing indicates
that the resultant executables operate correctly without it; ignoring it
is the simplest solution.

All Quake projects now correctly compile without errors.