[BUG #7395] file id and line numbers for warnings from JSDoc parsing

- maintain relative line numbers of JSDoc's (in Comment.py#lines_to_sections)
- attribute each .parse entry with a 'line' member
- feed JSDoc entries with errors/warnings to the caller
- print those entries in the caller (e.g. .parseNode), calculating actual line
  number
[BUG #7395] minor clean-up
[BUG #7395] basing lint.py#get_at_hints on Hint() tree

- finally!
- this also fixes multiple occurrences of the same warning
- should also be faster
[BUG #7395] make classId deduction more robust
[BUG #7395] process JSDoc errors when parsing __init__.js package docs