M1_M3/M6_MX: Wait for net devices to come up

Based on https://github.com/Pivosgroup/buildroot-linux commits 77bc498c48d83e9c6094b769fc0ea6b9d41f2a6a & a083da1c0a7bf153e8e43bf38f2a41efdafb5f63
Add OpenGL API 19 from published Amlogic buildroot
AML: Cleanup OpenGL package

- Set apiv20 as default for M6
- Rename apiv14 > apiv9 (Actual version)
- Repack apiv9 properly
- apiv19 depends on softflot
M1_M3/M6_MX: Prep overlays for ifplugd package
CONFIGS: Update MX Linux configs (enable ifplugd)
M1_M3/M6_MX: Restart ntpd when ifplugd brings up a interface
M1_M3/M6_MX: NetworkManager use ifplugd to control eth0
Remove confluence_powerbutton.patch to be able to reboot the system.
Unhide all settings in XBMC by default for G18REF_MX2REF boards.
Switch to latest XBMC Gotham beta.
Use default XBMC splash screen.
Merge remote-tracking branch 'upstream/2013.11-Amlogic' into 2013.11-Amlogic
Use kernel from GIT repository fot G18-MX2 configuration.