Restore legacy datelc, fix ConfigFile error path, and sanitize CSV author names

[shbhmexe]

This PR makes small, safe corrections that improve stability and correctness without changing behavior or adding features:

1. Restore legacy datelc file (cncfdm.py)

• Problem: src/tests/gitdm-tests.py expects a datelc file for the -D path, but cncfdm only wrote datelc.csv.
• Fix: Write both datelc.csv (modern, with header) and legacy datelc (fixed‑width, no header) like the historical gitdm.py did.
• Impact: Tests and existing downstream scripts relying on datelc work again; no change to CSV output.

2. Correct error path in ReadFileType() (ConfigFile.py)

• Problem: Code called ConfigFile.croak, which referenced a function attribute that doesn’t exist; on malformed lines this would raise the wrong exception.
• Fix: Call module‑level croak() directly.
• Impact: Proper, user‑friendly error handling on bad file‑type config lines.

3. CSV output hygiene (csvdump.py)

• Problem: Author name was sanitized, then immediately overwritten, dropping quote/backslash sanitization; CSV files were left unclosed.
• Fix: Sanitize once (quotes, backslashes, apostrophes) then email_encode; close CSV files after writing.
• Impact: More robust CSVs on Windows and fewer chances of malformed fields; semantics unchanged.

4. Indentation normalization (cncfdm.py, gitdm.py)

• Problem: Mixed tabs/spaces in a small block under --numstat handling.
• Fix: Convert those lines to spaces; no logic changes.
• Impact: Avoids potential TabError/formatting issues; behavior identical.

Verification

• Changes are isolated and additive.
• The -D flow now emits both datelc.csv and datelc (legacy), matching expectations in src/tests/gitdm-tests.py.
• No core counting logic, parsing, or report math was changed.
• CSV headers and rows are unchanged except for safer author-name sanitization (previously intended but accidentally bypassed).

Risk assessment

• Very low. The only observable output change is the presence of the legacy datelc file (additive) and correctly sanitized author names in ChangeSets CSVs.

How to test

• Run the regression tests from repo root:
  • python src/tests/gitdm-tests.py
• Or quick smoke‐test for -D path:
  • git --git-dir src/tests/testrepo log -p -M | ./gitdm -D
  • Verify both datelc and datelc.csv are created and datelc matches src/tests/expected-datelc.
    xpected by tests. No breaking changes.