abort in extract_identifier if an identifier cannot be found

- previously due to a logic bug this would just return the
  original line (value[0:-1])
categorize --flush-privileges section

- If --flush-privileges is used in a mysqldump there will be
  a section immediately after the "mysql" system database
  creation that issues a FLUSH PRIVILEGES.  This is noted
  by a comment block that starts with "-- Flush Grant Tables",
  which categorize_section() now detects properly
tweak parse_section() terminate condition

- previously parse_section terminated when it saw any line
  that started with a sql comment ("--"); now it terminates
  only on a blank comment indicating the start of a comment
  block (line == "--").  This fixes the problem of parsing
  --master-data=2 where the change master line is a comment
  and also has the effect of folding the "Dump completed"
  line into the footer which is currently ignored by default
  anyway.
output skipped lines to debug output
update CHANGES for issue#33

- Resolves issue #33
Merge branch 'feature/issue#33' into develop
bump version to 1.0.8-dev