idealwireless: step1 - added NED, MSG
idealwireless: step2 - added implementation
linklayer: moved WirelessMacBase to common folder

this module used by:
  - IdealWirelessMac module in src/linklayer/idealwireless folder
  - Ieee80211Mac module in src/linklayer/ieee80211/mac folder
idealwireless: ChangeLog
idealwireless: added examples and tests

--examples
idealwireless: added as feature