Incorrect output regex on certain inputs.

[IQuick143]

When the words fed into the trie are a prefix of an other word, the regex outputted is not correct.

Example code used to reproduce bug:

import triegex

def RegexFromList(listOfWords):
	t = triegex.Triegex()
	for i in listOfWords:
		t.add(i)
	return t.to_regex()

print(RegexFromList(["TEST", "TE", "TEXT", "BANANA"]))

This code outputs: (?:XT\b|TE\b|~^(?#match nothing))
Which happens to match TE correctly but matches XT too and doesn't match TEXT, TEST, BANANA as would be expected.

Expected Regex would be: (?:TE(?:\b|XT\b|ST\b)|BANANA\b|~^(?#match nothing)) or equivalent.

[IQuick143]

I've written a fix for this bug but it involves rewriting the whole TrierexNode.to_regex() method and my implementation is recursive (but very simple), all unit tests pass.

Is the recursion okay, or must I rewrite it into a loop? (not trivial in this case)

[IQuick143]

Either way I've made an iterative implementation.

[ZhukovAlexander]

@IQuick143 thanks for your work, I'll release the new version to PyPI as soon as I can.