* add reingold tillford tree layout algorithm
* add first silly implementation of matplotlib based plotting for trees
* object oriented design for export_graphviz so it can be extended
* add class for mlp export
* add colors
* separately scale x and y, add arrowheads, fix strings
* implement max_depth
* don't use alpha for coloring because it makes boxes transparent
* remove unused variables
* vertical center of boxes
* fix/simplify newline trimming
* somewhere in the middle of stuff
trying to get rid of scalex, scaley
* remove "find_longest_child" for now, fix tests
* make scalex and scaley internal, and ax local.
render everything once to get the bbox sizes, then again to actually plot it with known extents.
* add some margin to the max bbox width
* add _BaseTreeExporter baseclass
* add docstring to plot_tree
* use data coordinates so we can put the plot in a subplot, remove some hacks.
* remove scalex, scaley, add automatic font size
* use rendered stuff for setting limits (well nearly there)
* import plot_tree into tree module
* set limits before font size adjustment?
* add tree plotting via matplotlib to iris example and to docs
* pep8 fix
* skip doctest on plot_tree because matplotlib is not installed on all CI machines
* redo everything in axis pixel coordinates
re-introduce scalex, scaley
add max_extents to tree to get tree size before plotting
* fix max-depth
parent node positioning and don't consider deep nodes in layouting
* consider height in fontsize computation
in case someone gave us a very flat figure
* fix error when max_depth is None
* add docstring for tree plotting fontsize
* starting on jnothman's review
* renaming fixes
* whatsnew for tree plotting
* clear axes prior to doing anything.
* fix doctests
* skip matplotlib doctest
* trying to debug circle failure
* trying to show full traceback
* more print debugging
* remove debugging crud
* hack around matplotlib <1.5 issues
* copy bbox args because old matplotlib is weird.
* pep8 fixes
* add explicit boxstyle
* more pep8
* even more pep8
* add comment about matplotlib version requirement
* remove redundant file
* add whatsnew entry that the merge lost
* fix merge issue
* more merge issues
* whitespace ...
* remove doctest skip to see what's happening
* added some simple invariance tests buchheim function
* refactor
___init__ into superclass
* added some tests of plot_tree
* put skip back in, fix typo, fix versionadded number
* remove unused parameters special_characters and parallel_leaves from mpl plotting
* rename tests to test_reingold_tilford
* added license header from pymag-trees repo
* remove duplicate test file.
Renamed Visitor to Exporter
Moved all write functions into the exporter
Removed Leaf class (only use Node class, so that samples and error are shown)
Assign nodes a repeatable unique id
Replaced .png files with .svg files
Thomas J. Fan