Remove trailing newline from version file if necessary (a9183756-gh#27)

* Remove trailing newline from version file if necessary

This fixes the first part of a9183756-gh#25, as this could lead to invalid
multiline build recipes

* Changed regex to cmake string strip function

Author: RobertWilbrandt

Arduino/System/BoardToolchain.cmake

@@ -101,6 +101,7 @@ function (SetupBoardToolchain)
 	set(_path "${ARDUINO_TOOLCHAIN_DIR}")
 	if (EXISTS "${ARDUINO_INSTALL_PATH}/lib/version.txt")
 		file(READ "${ARDUINO_INSTALL_PATH}/lib/version.txt" _version)
+                string(STRIP "${_version}" _version)
 		if(_version)
 			set(_path "${ARDUINO_INSTALL_PATH}")
 			string(REPLACE "." "0" _version "${_version}")