- file-to-memory save
- incremental difference steps (compression)
everthing has been tightly coded to use minimum of memcpy or allocs. In
fact this system works with a single full buffer (=file) in memory, and undosteps as differences from it.
Speed gain is factor 4-8 faster. I've added it in CTRL+ALT+T timer menu for
a test. Please note the gain is especially in the undo-storing, not in
retrieving undo.
Also new: file read option to skip UI read (file menu). This now also is
default for the undo system.
