Add Release-MinDep solution configuration
Use splice rather than swaps to pop the undo stack
Make BaseGrid::UpdateMaps far less slow
Redesign the undo stack

Store the data in vectors rather than AssFiles since even an intrusive
linked list has comically high memory overhead. Cuts memory usage of a
full undo stack with 15k lines by 65 MB for 32-bit and 130 MB for
64-bit. Also roughly halves how long it takes to copy the file for the
undo stack, and makes undo/redo a bit faster.