add line break between paragraphs in baker command help

- baker 1.3's upstream behavior is to reformat each paragraph
  but leave no space between paragraphs.  This makes reading
  somewhat more difficult for long command descriptions that
  are broken into multiple separate paragraphs.  This trivial
  patch adds a line break between paragraphs.
minimize the cases where baker output info about 'double hyphens'

- if there are required arguments (parameters without a default
  value), baker is helpful and indicates you can treat command
  line options as *only* positional arguments by using a '--'
  separator. baker 1.3 currently detects this by checking if
  there is no default value, but use None as a sentinel. None
  is used by dbsake as a default for various options which are
  not strictly required. This patch restricts this message output
  to cases where there are really required parameters with no
  default value.
bump dbsake.thirdparty.tempita to 0.5.3
abort split-mysqldump on invalid input

- previously header() would consume an unbounded number of lines
  until an empty line was found. now some basic checking on the
  format of the lines is done to abort early.
  Resolves issue #17
cleanup exception handler output
handle 5.0 .frm "extra" sections

- 5.0 .frm files lack partition clauses and will have a short
  extra section as a result.  frm-to-schema would abort as too
  few bytes would be read when reading extra table attributes
  Resolves issue#14
handle relative --sandbox-directory

- relative --sandbox-directory paths were not be resolves to
  absolute paths and caused various failures when used in
  MySQL options as-is.  This now resolves sandbox-directory up
  front to an absolute path.
  Resolves issue #15.
Merge branch 'feature/issue#14' into develop
Merge branch 'feature/issue#17' into develop
handle non-executable mysqld more elegantly

- previously stderr was being lost and the sandbox command would
  generate an uncaught exception.  Now OSError is trapped and a
  more useful error message is output. stderr is "leaked"
  intentionally when running mysqld --version, so any obvious
  linking errors can be output on stderr without interference
  from dbsake
  Resolves issue #13
set innodb-data-file-path to match datadir

- if --data-source is provided and puts existing shared ibdata
  tablespaces in the datadir, ensure the my.sandbox.cnf has a
  matching innodb-data-file-path to match both the number and
  size of these tablespaces.
  Resolves issue #12
update regex used to match indexes for deferment

- allow split-mysqldump to handle indexes that specify an algorithm
  previously the regex would fail to match and such indexes would
  not be considered for deferring.
  Resolves issue #10.
add progress indicators to start/stop actions

- start/stop will now emit a '.' once per second until the mysql
  finishes the operation or fails.  This gives a little more
  feedback when a process is in the process of starting or
  stopping but taking some time.
  Resolves issue #18
mark blob types as never having a default

- previously only next_number (auto_increment) fields or fields
  specifically marked with a no_default field flag were skipped
  during defaults processing.  This additionally adds any field
  with a blob utype - which should cover any blob or text field
  which do not support a default value in any current version of
  MySQL. This fixes an issue with processing certain .frm files
  generated by MariaDB where blob/text fields might not have
  the NO_DEFAULT fieldflag set, but still does not have a default
  due to the column type being a blob type.
  Resolves issue #9
quote defaults for integer types

- previously integer type defaults were output as DEFAULT N where
  N was a bare integer value.  Further if N was 0, dbsake would
  wrongly assume the value was missing.  No default processing
  always quotes the integer, so the default is now output as
  DEFAULT '0'.  This better matches the output from SHOW CREATE
  TABLE and avoids the issue of missing default values when the
  default is zero.
  Resolves issue #11
update CHANGES for recently merged feature branches