Major plugin refactor and cleanup.

Switched to POCO library for unified platform/library interface.
Deprecated the external module API. It was creating more problems than solving.
Removed most built-in libraries in favor of system libraries for easier maintenance.
Cleaned and secured code with help from static analyzers.

vendor/POCO/Util/samples/SampleApp/CMakeLists.txt

@@ -0,0 +1,5 @@
+add_executable(SampleApp src/SampleApp.cpp)
+if(WINCE)
+	set_target_properties(SampleApp PROPERTIES LINK_FLAGS "/ENTRY:wmainCRTStartup")
+endif()
+target_link_libraries(SampleApp PUBLIC Poco::Util Poco::JSON Poco::XML)