Added a new optional audio sink as a test

new_portaudio_sink/CMakeLists.txt

@@ -0,0 +1,35 @@
+cmake_minimum_required(VERSION 3.13)
+project(new_portaudio_sink)
+
+if (MSVC)
+    set(CMAKE_CXX_FLAGS "-O2 /std:c++17 /EHsc")
+else()
+    set(CMAKE_CXX_FLAGS "-O3 -std=c++17 -fpermissive")
+endif (MSVC)
+
+file(GLOB SRC "src/*.cpp")
+
+include_directories("src/")
+
+add_library(new_portaudio_sink SHARED ${SRC})
+target_link_libraries(new_portaudio_sink PRIVATE sdrpp_core)
+set_target_properties(new_portaudio_sink PROPERTIES PREFIX "")
+
+if (MSVC)
+    find_package(portaudio CONFIG REQUIRED)
+    target_link_libraries(new_portaudio_sink PUBLIC portaudio)
+else (MSVC)
+    find_package(PkgConfig)
+
+    pkg_check_modules(PORTAUDIO REQUIRED portaudio-2.0)
+
+    target_include_directories(new_portaudio_sink PUBLIC ${PORTAUDIO_INCLUDE_DIRS})
+
+    target_link_directories(new_portaudio_sink PUBLIC ${PORTAUDIO_LIBRARY_DIRS})
+
+    target_link_libraries(new_portaudio_sink PUBLIC ${PORTAUDIO_LIBRARIES})
+
+endif (MSVC)
+
+# Install directives
+install(TARGETS new_portaudio_sink DESTINATION lib/sdrpp/plugins)