Updated AppVeyor configuration

Add dependencies for sound backends
Exclude travis test branches from build
Set git clone depth to one

.appveyor.yml

@@ -1,5 +1,11 @@
 version: "{build}"
 
+branches:
+  except:
+    - /^travis.*$/
+
+clone_depth: 1
+
 os: Visual Studio 2015
 
 platform: 
@@ -10,12 +16,37 @@ configuration:
   - Debug
   - Release
 
+cache:
+  - ci_deps_win_v01.zip
+
+environment:
+  # Update dependencies here: https://github.com/coelckers/gzdoom/releases/tag/ci_deps
+  DEPS_URL: https://github.com/coelckers/gzdoom/releases/download/ci_deps/
+  DEPS_FILENAME: ci_deps_win_v01.zip
+
+install:
+  - if not exist "%DEPS_FILENAME%"
+    appveyor DownloadFile "%DEPS_URL%%DEPS_FILENAME%"
+  - 7z x -y "%DEPS_FILENAME%"
+
 before_build:
-  - cmd: md build
-  - cmd: cd build
-  - cmd: if "%platform%"=="Win32" set CMAKE_GENERATOR_NAME=Visual Studio 14 2015
-  - cmd: if "%platform%"=="x64"   set CMAKE_GENERATOR_NAME=Visual Studio 14 2015 Win64
-  - cmd: cmake -G "%CMAKE_GENERATOR_NAME%" -DCMAKE_BUILD_TYPE=%configuration% ..
+  - md build
+  - cd build
+  - if "%PLATFORM%"=="Win32" set CMAKE_GENERATOR_NAME=Visual Studio 14 2015
+  - if "%PLATFORM%"=="x64"   set CMAKE_GENERATOR_NAME=Visual Studio 14 2015 Win64
+  - set DEPS_INCLUDE_DIR=%APPVEYOR_BUILD_FOLDER%\ci_deps_win\include
+  - set DEPS_LIB_DIR=%APPVEYOR_BUILD_FOLDER%\ci_deps_win\lib\%PLATFORM%
+  - cmake -G "%CMAKE_GENERATOR_NAME%" -T "v140_xp"
+    -DCMAKE_BUILD_TYPE="%CONFIGURATION%"
+    -DFMOD_INCLUDE_DIR="%DEPS_INCLUDE_DIR%"
+    -DFMOD_LIBRARY="%DEPS_LIB_DIR%\fmodex.lib"
+    -DOPENAL_INCLUDE_DIR="%DEPS_INCLUDE_DIR%"
+    -DOPENAL_LIBRARY="%DEPS_LIB_DIR%\OpenAL32.lib"
+    -DMPG123_INCLUDE_DIR="%DEPS_INCLUDE_DIR%"
+    -DMPG123_LIBRARIES="%DEPS_LIB_DIR%\libmpg123-0.lib"
+    -DSNDFILE_INCLUDE_DIR="%DEPS_INCLUDE_DIR%"
+    -DSNDFILE_LIBRARY="%DEPS_LIB_DIR%\libsndfile-1.lib"
+    ..
 
 build:
   project: build\GZDoom.sln