When pressing one of cursor keys in REPL, user gets results like niecza> ^[[A^[[B^[[C^[[D. This makes it annoying to actually use REPL.
There is an external program rlwrap which you can install to work around this, for instance instead of running niecza run rlwrap niecza. A proper fix will come later.
Lift the (X11 license) line editor from csharp.exe. it's not readline…
… but it's something. fixes #148
Now arrows do work, but when any error appears, the REPL shows cursor in wrong place. It only happens when the prompt wouldn't be at bottom of the console window (in most cases it's already at bottom), so it's usually not really important.