re-add Windows visual studio build back into the travis-ci tests

New procedures added to win/win32/vs2017/travisci.sh for travis-ci testing.

- use curl to obtain Lua from http://www.lua.org/ftp/lua-5.3.5.tar.gz
- use tar to unzip lua into lib/lua-5.3.5/...

Note: curl and tar were both added as part of Windows 10 in late Dec 2017
   https://techcommunity.microsoft.com/t5/Containers/Tar-and-Curl-Come-to-Windows/ba-p/382409

- use git to clone pdcurses into lib/pdcurses
- use git to clone universal-ctags into lib/ctags
- build universal-ctags ahead of building NetHack + lua + pdcurses
- adjust sys/winnt/Makefile.msc to look for those things in their lib locations when
  building under travis

.travis.yml

@@ -69,6 +69,11 @@ matrix:
               sed -i 's/^#define TEXTCOLOR//'     include/unixconf.h
               make fetch-lua && make install
               cat dat/options
+    - os: windows
+      env: DESCR=windows-visualstudio
+      language: shell
+      script:
+        - ./win/win32/vs2017/travisci.sh
     - os: linux
       env: DESCR=msdos-cross-on-linux HINTS=linux LUA_VERSION=5.3.5
       compiler: gcc
@@ -80,11 +85,6 @@ matrix:
         - sh sys/msdos/msdos-cross-compile.sh
   exclude:
     - os: windows
-      env: DESCR=windows-visualstudio
-      language: shell
-      script:
-        - ./win/win32/vs2017/travisci.sh
-    - os: windows
 #     install: choco install mingw
       env: DESCR=windows-mingw
       script: