Show user info in the status bar when selecting a treenode

Rather than showing object tree information in the status bar when
selecting a tree node, show the same authorship and review user
information as when pressing "i", with node and skeleton IDs included.
Closes acardona/CATMAID#699.
Add default port to database connection script

The default port is used if the ~/.catmaid-db file doesn't contain it. This
fixes #454.
Prevent division by zero in skeleton measurement

When computing weighted position for slab nodes in skeleton measurement,
do not adjust weighted position in edge case where child distances are
zero to prevent division by zero. Closes acardona/CATMAID#550.
Merge branch 'issues/699-node-status' from 'aschampion/CATMAID'
Cropping: add maximum file size setting

This commit adds a maximum allowed file size to the settings and the cropping
module. It can be adjusted by changing the GENERATED_FILES_MAXIMUM_SIZE setting
(in Bytes) which defaults to 50MB. The cropping module is estimating the final
file size by summing up the size of each image part it needs to create the final
image stack. The size of a single part is estimated by multiplying the size of
the tile it is referring to with the ratio of actually used area of it. This
fixes #730.
DELETE key deletes active node or connector

DELETE (FN + DELETE on mac) now deletes the active node or connector.
Note that this replaces the mapping of numpad delete/., which previously
mapped to slice movement. Closes acardona/CATMAID#121.
SVG Overlay: fix skeleton selection when split

When splitting, wait for node update before selecting the new active
node to prevent the wrong skeleton from being activated. Closes
acardona/CATMAID#589.
SVG Overlay: fix missing semicolons (minor)