802.1Q NX-OS configuration parser merged with IOS

Now the single code parses both NX-OS and IOS configuration.
'show interface switchports' command output is used to determine
switchport list. Hence proper switchport detecton for NX-OS.
Do not return 'none' port mode for IP interfaces and other non-switched
ports.

ios12ReadVLANConfig: begin with ios12-get8021q-swports, not ios12-get8021q-top
ios12ScanTopLevel: first letter case insensivity for Port-channels
ios12ReadSwitchPortList: new function to read switchport list
ios12PickSwitchportCommand: support empty line separators, fex-fabric
mode, change in 'none' mode logic
ios12PickSwitchportCommand: support for dual-space NX-OS indent
ios12PickVLANCommand: removed hardcoded separator constant
vrp55Read8021QConfig: change in 'none' mode logic
ios12TranslatePushQueue: added switport list command

-nxos4Read8021QConfig: removed
-nxos4ScanTopLevel
-nxos4PickVLANCommand
-nxos4PickSwitchportCommand