improve frappy.errors

- include all secop errors from spec
- add doc strings
- make conversion to and from error report nicer
- move all error classes to frappy.errors
- rename errors clashing with built-in errors

Change-Id: I4d882173b020cd4baf862c5891375b691e67e24a
Reviewed-on: https://forge.frm2.tum.de/review/c/secop/frappy/+/30721
Tested-by: Jenkins Automated Tests <pedersen+jenkins@frm2.tum.de>
Reviewed-by: Markus Zolliker <markus.zolliker@psi.ch>

frappy/datatypes.py

@@ -29,7 +29,7 @@ import sys
 from base64 import b64decode, b64encode
 
 from frappy.errors import WrongTypeError, RangeError, \
-    ConfigError, ProgrammingError, ProtocolError
+    ConfigError, ProgrammingError, ProtocolError, DiscouragedConversion
 from frappy.lib import clamp, generalConfig
 from frappy.lib.enum import Enum
 from frappy.parse import Parser
@@ -45,11 +45,6 @@ UNLIMITED = 1 << 64  # internal limit for integers, is probably high enough for
 Parser = Parser()
 
 
-class DiscouragedConversion(WrongTypeError):
-    """the discouraged conversion string - > float happened"""
-    log_message = True
-
-
 def shortrepr(value):
     """shortened repr for error messages