* Multiple start functions are allowed

The '--main' option can be given multiple times.  A separate graph
will be drawn for each function given as its argument.

* New option --target=FUNCTION

If this option is given, the produced graph will contain only paths
leading from start function (or functions) to the given FUNCTION.

Multiple '--target' options are allowed.

* New output format: dot

The '-f dot' (or '--format=dot') option instructs cflow to output
graph as a description in DOT language, suitable as input to graphviz
programs.

* cflow-mode: new commands for navigating in the graph:

  c   go to the calling function
  n   go to the next function at the same nesting level
  p   go to the previous function at the same nesting level

* Bugfixes:

** CVE-2019-16165
** CVE-2019-16166
** Fix parsing of K&R style function declarations
** Improve parsing of typecasts
** Fix recursive call detection