Fixed the longstanding xterm problem.

For ages I've had problems with 256-color xterm and vim.  I never
used a proper colorscheme, but just modified the default I was
"magically" given.  This changes all of that to make us now have
a proper color scheme -- the "adam" scheme.

Colors now work independent of console color depth, I think.
There are remaining quirks, but I'll have to add the requirements
as proper color mappings to my color scheme file.

vim/after/syntax/netrw.vim

@@ -0,0 +1,5 @@
+" I extend the netrw scripts from vim to process source files in nice colors.
+
+if exists("g:netrw_special_syntax") && netrw_special_syntax
+ syn match netrwSrc		"\(\S\+ \)*\S\+\.\%(c\|cpp\|cxx\|cc\)\>"			contains=netrwTreeBar,@NoSpell
+endif