Reworked Node Creation in TopBar
Link Creation in TopBar now comes with property-value fields; still some problems with topbar-instructions though
#toplink-instructions is no longer edited by LinkHover or Expander while a link is being created
Resolved merge conflicts
Fixed some bugs in TopBarCreate
Can now cancel link creation before target is chosen
Added url fields
Merge pull request #127 from willzeng/topbarcreate

Refactor of TopBarCreate!