Bugs: strings, identifiers and security formats (0.28.1) #35

Defects in the string, identifier and security-format value objects of 0.28.1 (each one reproduced). Fixed by the new strings.py, identifiers.py and security.py families; every item gets a regression test and is ticked when the fix lands.

• C19 Uuid4 accepts non-v4 UUIDs (v1/v3/v5, nil) and malformed strings: uuid.UUID(s, version=4) overwrites the version instead of checking it.
• C20/C42 uuid4_test.test_old_uuid_version_raise_error passes only because of the str type check, hiding C19.
• X06 Uuid4 accepts UUID strings written with non-ASCII digits, which then compare unequal to the ASCII form.
• C21/C53 Cpe uses invalid escape sequences in a non-raw regex: SyntaxWarning on 3.12+, and import pyvalueobjects fails under -W error.
• C22 Every regex VO accepts a trailing newline ('$' anchor with re.match): Cve('CVE-2014-9418\n').
• C23 Cve, Cpe and Url accept non-ASCII Unicode digits because the patterns use \d (Cve('CVE-٢٠١٤-٩٤١٨')).
• C29 Cpe rejects common valid CPE 2.2 URIs (empty components, language, short names, percent-encoding) and every CPE 2.3 formatted string.
• C30 Equal identifiers compare unequal: case-insensitive or multi-format values (hashes, UUIDs, MACs, CVEs) are stored verbatim without canonicalisation.