how to upgrade mmc manually:
1. overwrite mcu: vmcu_mmc.exe + all the .dll files in mcu folder + all the .db files in mcu folder
2. overwrite web(the whole folder): ~/webapp/web
3. overwrite locale(the whole folder): ~/webapp/locale
4. copy jnjencryptor: ~/webapp/bin/jnjencryptor/jnjencryptor.exe
5. copy jed: ~/webapp/bin/jed/jed.exe
6. check the difference and modify the two ini files:
~/mcu/configm.ini + ~/webapp/config/mmc.ini
7. if the old MCU and new MCU use different DH key size, re-create key pairs. MCU starts to use 2048bit key from version 3.23.1.
  7.1a Linux
    ~/mcu/mcu_mmc --identity="~/webapp/key/key_web_localhost" --passphrase=autogenerate --keypair
    ~/mcu/mcu_mmc --identity="~/mcu/key_mcu_localhost" --passphrase=autogenerate --keypair
  7.1b Windows
    cd ~/mcu
    mcu_mmc.exe -keypair key_mcu_localhost
	cd ~/webapp/key
	~/mcu/mcu_mmc -keypair key_web_localhost
  7.2 copy MCU's public key files to web folder and copy web's public key files to MCU folder