Remote TCP updates:

Add support for public list of SDRangel servers that can be displayed on Map.
Add FLAC and zlib IQ compression.
Add IQ squelch for compression.
Add remote device/antenna position and direction reporting.
Add text messaging.

cmake/Modules/FindFLAC.cmake

@@ -0,0 +1,31 @@
+IF(NOT FLAC_FOUND)
+    INCLUDE(FindPkgConfig)
+    PKG_CHECK_MODULES(PC_FLAC flac)
+
+    FIND_PATH(
+        FLAC_INCLUDE_DIR
+        NAMES FLAC/stream_encoder.h
+        HINTS ${PC_FLAC_INCLUDE_DIRS}
+        PATHS /usr/local/include
+              /usr/include
+    )
+
+    FIND_LIBRARY(
+        FLAC_LIBRARY
+        NAMES FLAC
+              libFLAC
+        HINTS ${FLAC_DIR}/lib
+              ${PC_FLAC_LIBRARY_DIRS}
+        PATHS /usr/local/lib
+              /usr/lib
+              /usr/lib64
+    )
+
+    message(STATUS "FLAC LIBRARY " ${FLAC_LIBRARY})
+    message(STATUS "FLAC INCLUDE DIR " ${FLAC_INCLUDE_DIR})
+
+    INCLUDE(FindPackageHandleStandardArgs)
+    FIND_PACKAGE_HANDLE_STANDARD_ARGS(FLAC DEFAULT_MSG FLAC_LIBRARY FLAC_INCLUDE_DIR)
+    MARK_AS_ADVANCED(FLAC_LIBRARY FLAC_INCLUDE_DIR)
+
+ENDIF(NOT FLAC_FOUND)