Generalize Picoscope interface

This allows the Block to be extended with support for various Picoscope
models.

Furthermore, this ports the custom work implementation to processBulk()
and implements the inclusion of timing messages received over the
message port.

Fixes #113

blocklib/picoscope/CMakeLists.txt

@@ -5,10 +5,16 @@ set_property(TARGET ps4000a PROPERTY
 target_link_libraries(ps4000a INTERFACE PkgConfig::zlib PkgConfig::libusb)
 target_include_directories(ps4000a INTERFACE ${PICOSCOPE_PREFIX}/include/libps4000a ${PICOSCOPE_PREFIX}/include/libps5000a) # Hack: PicoCallback.h is missing in libps4000a/
 
+add_library(ps5000a SHARED IMPORTED GLOBAL)
+set_property(TARGET ps5000a PROPERTY
+             IMPORTED_LOCATION ${PICOSCOPE_PREFIX}/lib/libps5000a.so)
+target_link_libraries(ps5000a INTERFACE PkgConfig::zlib PkgConfig::libusb)
+target_include_directories(ps5000a INTERFACE ${PICOSCOPE_PREFIX}/include/libps5000a)
+
 add_library(fair-picoscope INTERFACE)
 target_include_directories(fair-picoscope INTERFACE $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}> $<INSTALL_INTERFACE:include/>)
 
-target_link_libraries(fair-picoscope INTERFACE ps4000a gr-digitizers-options gnuradio-core refl-cpp fmt)
+target_link_libraries(fair-picoscope INTERFACE ps4000a ps5000a gr-digitizers-options gnuradio-core refl-cpp fmt)
 set_target_properties(gr-digitizers PROPERTIES PUBLIC_HEADER "Picoscope.hpp;Picoscope4000a.hpp;StatusMessages.hpp")
 
 if (ENABLE_GR_DIGITIZERS_TESTING)