PEP8 formatting in Bio.HotRand; Use increment operator
The Bio.HotRand.hex_convert function was removed 3 years ago
Fix Bio.HotRand under Python 3.

Until recently the (online) test for Bio.HotRand was
silently passing without actually testing the code,
so we never noticed it was broken under Python 3 :(

In anycase, this module has been deprecated.
Apply 2to3 has_key fixer to Bio.trie

I appear to have wrongly been under the impression that
the C code in Bio/triemodule.c would need updating too.

$ 2to3 --no-diffs -n -w -f has_key Bio BioSQL Tests Doc Scripts
RefactoringTool: Refactored Bio/triefind.py
RefactoringTool: Refactored Tests/test_trie.py
RefactoringTool: Files that were modified:
RefactoringTool: Bio/triefind.py
RefactoringTool: Tests/test_trie.py
No longer need the 2to3 has_key fixer
Use assertTrue and assertFalse in test_trie.py
Don't need 2to3 instances fixer now.

$ 2to3 --no-diffs -n -w -f isinstance -d Bio BioSQL Tests Doc Scripts
RefactoringTool: No files need to be modified.

$ 2to3 --no-diffs -n -w -f isinstance Bio BioSQL Tests Doc Scripts
...
(makes no changes, seems to consider it for a few files - odd)