Rename *.bat to *.cmd.

These batch files take advantage of newer functionality in NT cmd,
so they should be named *.cmd instead of *.bat.

appveyor.yml

@@ -18,7 +18,7 @@ configuration:
 
 before_build:
   - cd %APPVEYOR_BUILD_FOLDER%
-  - appveyor.bat
+  - appveyor.cmd
 
 build_script:
   - cd %APPVEYOR_BUILD_FOLDER%

scripts/CMakeLists.txt

@@ -10,8 +10,8 @@ IF(WIN32)
 	# Install the Windows batch files for
 	# registering and unregistering the DLL(s).
 	INSTALL(FILES
-		install.bat
-		uninstall.bat
+		install.cmd
+		uninstall.cmd
 		DESTINATION "."
 		COMPONENT "dll"
 		)

scripts/package.cmd

@@ -37,7 +37,7 @@ IF NOT EXIST travis.sh (
 	ECHO source directory. Change to the top-level source directory
 	ECHO and rerun this batch file by typing:
 	ECHO.
-	ECHO scripts\package.bat
+	ECHO scripts\package.cmd
 	ECHO.
 	PAUSE
 	EXIT /B 1