Date2decimal            convert Date to decimal format, eg "2014-05-05"
                        to "2014.34"
calculate_angle         Calculate angle coordinates for circular
                        layouts
calculate_branch_mid    Branch mid-point coordinates
clade_geometry          One call instead of three. Returns the left and
                        right boundary angles of the clade subtree, the
                        largest distance from 'node' to any node inside
                        the clade, and the largest distance from the
                        root of the whole tree to any node - the two
                        radii the clade label / hilight code needs.
decimal2Date            convert decimal format to Date, eg "2014.34" to
                        "2014-05-05"
getXcoord2              x coordinates from an edge list
getYcoord               y coordinates for tips
get_layout              Read the layout recorded on a layout result
layout_names            Layout names accepted by 'tree_layout()'
re_assign_ycoord_df     Re-assign y coordinates
tree_layout             Compute node coordinates for a tree
