Remove spurious matches caused by old versions of Fantomas
Fix parsing errors

Use Failure pattern from F# core to catch System.Exception.
OCaml.Compatibility's Failure is a distinctive exception.
Fix tactics to execute code in F# Interactive

Any term with "\" should have @ to be escaped correctly.

Change a few terms from values to functions to delay
StackOverflowExeception.

Right now stack is blown at STRIP_ASSUME_TAC in tactics.fs