1. support "make size", "make size-files", "make size-components" and "make size-symbols"
2. add esp-idf style link file including "esp8266.ld" and "esp8266.project.ld.in"
3. add link advaced generation file to components of esp8266 and spi_flash
"$(PROJECT_NAME).app1.bin", "$(PROJECT_NAME).app2.bin" and "$(PROJECT_NAME).ota.bin" at "build" directory.
Only upload "$(PROJECT_NAME).ota.bin" to the server.
Select the target flash and input "make ota flash" or "make ota flash monitor".
Update the OTA README.md for 1 MB flash.