better output like libassert

[Theramar]

Expected Behavior

add an optional (for performance reasons) libassert-like output:

• colors (syntax highlighting)

• expression diagnostics:

  values involved in assert expressions are displayed. Redundant diagnostics like 7 => 7 are avoided.

  assert(vec.size() > 7);
  

  

• custom messages should be displayed like extra diagnostics

• stack trace can be ignored.

Actual Behavior

Running "sum"...
  sum.cpp:11:FAILED [(3 > 0 and 41 == 42)]
FAILED

here "false" gives no hint:

main.cpp:4:FAILED [false]