Improve cmakelists for vcpkg building

- Remove forced /MT directive.
- Allow building for debug.
- Add option to prevent building of example apps.

CMakeLists.txt

@@ -1,6 +1,8 @@
 cmake_minimum_required (VERSION 3.7.0)
 project (DiscordRPC)
 
+option(BUILD_EXAMPLES "Build example apps" ON)
+
 # format
 file(GLOB_RECURSE ALL_SOURCE_FILES
     examples/*.cpp examples/*.h examples/*.c
@@ -51,4 +53,6 @@ add_library(rapidjson STATIC IMPORTED ${RAPIDJSON})
 # add subdirs
 
 add_subdirectory(src)
-add_subdirectory(examples/send-presence)
+if (BUILD_EXAMPLES)
+    add_subdirectory(examples/send-presence)
+endif(BUILD_EXAMPLES)