devel/eric6: update to 18.06

ChangeLog:

• bug fixes
• Editor
  • added a configuration option (Editor->Style page) to show the marker map on the left or right of the editor
  • added a context menu for the "fold" margin
  • improved handling of folded lines when using "go to" functions
  • resize auto complete list box to fit with contents
  • added a configuration option (Editor->autocomplete to set up maximum width and height of the auto complete list box
• Shell
  • resize auto complete list box to fit with contents
• pip Interface
  • added an action to install a locally available package/wheel
• Web Browser (NG)
  • improved the sending of the "Referer" header like it is done by Firefox