minor, provide export tool, writing a graph file in dot syntax

Signed-off-by: Sebastian Freundt <freundt@ga-group.nl>
minor, provide rtz_const_vtxlst_t globally (alias it via #define in rotz.c)

Signed-off-by: Sebastian Freundt <freundt@ga-group.nl>
minor, provide rotz_edg_iter() to traverse edges

Signed-off-by: Sebastian Freundt <freundt@ga-group.nl>
minor, copy intermediary vtxlst in rotz_edg_iter()

Signed-off-by: Sebastian Freundt <freundt@ga-group.nl>
minor, use rotz_edg_iter() for export

Signed-off-by: Sebastian Freundt <freundt@ga-group.nl>
Merge branch 'cmd/export' into next

* cmd/export:
  minor, use rotz_edg_iter() for export
  minor, copy intermediary vtxlst in rotz_edg_iter()
  minor, provide rotz_edg_iter() to traverse edges
  minor, provide rtz_const_vtxlst_t globally (alias it via #define in rotz.c)
  minor, provide export tool, writing a graph file in dot syntax
minor, support different output formats in rotz-export

Signed-off-by: Sebastian Freundt <freundt@ga-group.nl>
minor, adhere to group options and render both dot files and gml files in rotz-export

Signed-off-by: Sebastian Freundt <freundt@ga-group.nl>
Merge branch 'cmd/export' into next

* cmd/export:
  minor, adhere to group options and render both dot files and gml files in rotz-export
  minor, support different output formats in rotz-export
Merge branch 'next'

* next:
  minor, adhere to group options and render both dot files and gml files in rotz-export
  minor, support different output formats in rotz-export
  minor, use rotz_edg_iter() for export
  minor, copy intermediary vtxlst in rotz_edg_iter()
  minor, provide rotz_edg_iter() to traverse edges
  minor, provide rtz_const_vtxlst_t globally (alias it via #define in rotz.c)
  minor, provide export tool, writing a graph file in dot syntax