List Commands Library for 50g

[DavidM]

I've added several new commands and made some minor performance improvements. All but one of the new commands are in a new category: stack manipulation. While not directly list-related, these new commands can still be a useful part of preparing data from (or to be added to) a list.

Here's a brief description of what's been added:

Stack Operations (STACK menu)
NMDUP - replicates a group of stack levels as indicated
NMROT - rotates stack items as indicated
SWPXY - swaps the indicated stack levels
DRPXY - drops the stack levels indicated in the range from X to Y
REVN - reverses the order of N stack levels

Element Grouping (GROUP menu)
SLST→ - LIST→ that avoids Garbage Collection issues for large lists

If anyone would be willing to try out the new commands, please send me a PM with an email address and I'll send you a preliminary "test" version of the library. It comes with a special testing function that exercises every command with a variety of different system configurations.

I've also been creating UserRPL versions of all the library commands in preparation for doing some performance comparisons. This is taking some time. To simplify the code, I've opted to ignore some of the edge cases for certain functions. My interest is more in comparing the general performance than in handling every possible edge case that the library code anticipates. I'm only about halfway through the command list so far, so there's still lots of work to do in this area.