Create stdpp-unstable package and add bitblast library
This MR adds a stdpp-unstable
library similar to the corresponding library in Iris. In general, the process for stdpp-unstable
follows the process for the corresponding Iris library and the most important points are documented in the README changes of this MR.
Additionally, this MR adds a bitblast tactic as the first unstable library.
Edited by Michael Sammler