stbt-templatematch: Fix deprecation warning

Introduced in eb658d20.
stbt.in: Mention `stbt batch` in `stbt --help` output

This was missing from commit f08a5de9.
stb-tester.spec: Update RPM description

To match the description on http://stb-tester.com
Bump stb-tester version to 0.18
stbt.py, stbt-templatematch: Reword "Weak match" to "No match"

For someone who is not familiar with the template match algorithm,
the log message "Weak match found" when the match gets through
the first pass but doesn't get through the second pass is misleading.

Reword the log message to
"No match found. Closest match: MatchResult(...)"
if no match found.

The message is the same
"Match found: MatchResult(...)"
if the template matches the screenshot.
stbt-templatematch: Do not print "match=True" if there is no match

stbt-templatematch incorrectly prints
"MatchResult(timestamp=0, match=True, ...)"
even if the template did not match the screenshot.

Print "match=False" in this case.
Merge remote-tracking branch 'szemate/reword-weak-match'

* szemate/reword-weak-match:
  stbt-templatematch: Do not print "match=True" if there is no match
  stbt.py, stbt-templatematch: Reword "Weak match" to "No match"
README.rst: Update subtitle to match description on stb-tester.com

I made a similar change to the description of the RPM package in
commit fde36144.
extra/openbuildservice.txt: Document that we build RPMs for Fedora 18-20 too
test_that_video_index_is_written_on_eos: Document new location of webminspector

The Chromium project has moved its git repositories.
stbt.py: [pylint 1.0] use new-style classes throughout

Pylint 1.0 insists on new-style classes, meaning that custom classes
must inherit from either `object` or another new-style class.
stbt.py: [pylint 1.0] disable certain instances of unused parameters

The functions in `Display` starting with `on_` and `restart_source`
are linked as callback to particular message types on bus, and which
must conform to certain patterns in their function signatures. The
parameters, such as _bus and _message, which are passed in are not used
by the functions, and this causes pylint to complain.

For `FakeDisplay.frames`, strictly speaking the `_timeout_secs` parameter
is *completely* unneeded, but as it is immitating the real `Display.frames`
it's nice to leave it there for better parallelism.
stbt lint: [pylint 1.0] work with either logilab.astng or astroid

Logilab renamed their `astng` module to `astroid`, but almost all of the
classes and functions that it includes have remained with the same name,
so we just include that import line in the 1.0 < pylint <= 1.0 try/except
block.

Note that I moved the E0611 (no-name-in-module) pylint warning to wrap
the entire block, and added F0401 (import-error) for `logilib.astng`.
stbt lint: '.png' does not count as a missing image file

The image path verifier should not raise an error for finding a string
that is *just* '.png' by declaring that the image does not exist on file.
It is completely understandable that users might want to use '.png' in
their code with it *not* referring to an image file. It would have to be
a hidden file, and I don't think anyone is crazy enough to use a hidden
file in their test scripts. '.png' is used as the `suffix` parameter
to a call to mktmp in stbt.py.

Note that the original regex was flawed in searching for r'.png' as this
matches any 4 character string ending with 'png' with '.' acting as a
wildcard. The new regex only returns True if it finds at least one
character followed by '.png', thus exluding simple '.png'
stbt-lint: do not exit with pylint 1.0, print warning instead

With the previous commits, stbt-lint now passes successfully against every
*.py in the stb-tester repository when using pylint 1.0, so there's no
real reason to not allow stbt-lint to run just because of this. Because
pylint 1.0 is still somewhat a work-in-progress, we print a warning
message instead which informs pylint 1.0 users to be careful.