bug fixes

This is a bug fix release:

• Nil map panic fixed when using dtx.AppendSuggestions()

• Hint text line proper blanked (this is a fix to a regression bug introduced in version 3.0.0)

• Example 01 updated to reflect API changes in 3.0.0

asynchronous updates / improved line wrapping

This release brings a considerable number of new features and bug fixes
inherited from readline's use in murex (https://github.com/lmorg/murex)

• Wrapped lines finally working (where the input line is longer than the
  terminal width)

• Delayed tab completion - allows asynchronous updates to the tab completion so
  slower suggestions do not halt the user experience

• Delayed syntax timer - allows syntax highlighting to run asynchronously for
  slower parsers (eg spell checkers)

• Support for GetCursorPos ANSI escape sequence (though I don't have a terminal
  which supports this to test the code on)

• Better support for wrapped hint text lines

• Fixed bug with $EDITOR error handling in Windows and Plan 9

• Code clean up - fewer writes to the terminal