When reading netlist or updating board from schematic, if the
changes leave a zone with a net with no pads then change the
zone's net to the new net of one of it's connections.
Also improves update-board-from-schematic's dry run reporting
to include zone nets and single-pad nets.
Fixes: lp:1609401
* https://bugs.launchpad.net/kicad/+bug/1609401
Replace all instances of "component" and "part" with "symbol" when
referring to schematic and library symbols.
Replace all instances of "component" with "footprint" when referring to
board and library footprints.
Minor dialog layout fixes to some of the dialogs impacted by the UI
string changes.
Jeff Young
Wayne Stambaugh
Fabrizio Tappero
jean-pierre charras
Tomasz Wlostowski