Add a multi channel example

Added a multi channel example with run limit, tilting and channel selection
features. Refs #1104 and closes #1111.

examples/relay_chn_multi/CMakeLists.txt

@@ -0,0 +1,10 @@
+# For more information about build system see
+# https://docs.espressif.com/projects/esp-idf/en/latest/api-guides/build-system.html
+# The following five lines of boilerplate have to be in your project's
+# CMakeLists in this exact order for cmake to work correctly
+cmake_minimum_required(VERSION 3.5)
+
+set(COMPONENTS main)
+
+include($ENV{IDF_PATH}/tools/cmake/project.cmake)
+project(relay_chn_single)