Summary of changes:
- Adding the p4runtime starter code and solution.
- Adding NO_P4, BMV2_SWITCH_EXE and P4C_ARGS to utils/Makefile
- Updated p4runtime/Makefile to use variables
- Adding conversion functions for match and action param values
- Separating P4Info and P4Runtime libraries
- Updating global README and adding p4runtime/README.md
- Disabling screen saver on VM GUI
- Adding desktop icons for Terminal, Wireshare and Sublime Text
- Updating topo.pdf -> png for Markdown viewing in basic_tunnel and
p4runtime READMEs
