The behavior of loadDepth has been reworked, with the goal being to arrange for error messages, signalled by code in a package that has been loaded without debugging mode enabled (see newPackage and loadPackage), to appear to come from the user's code instead (when the filename, line number, and column number of the error are displayed).
Fixed a bug: determinants and minors in rings over RR or CC would give wrong answers or even crash M2. The Bareiss strategy now gives an error in this case, and the Cofactor strategy is the default in this case. Additionally, pfaffians over such rings are now declared as not implemented.
The functions used with merge and combine now have a way to indicate that the resulting hashtable should have no entry corresponding to the current key.