fmbtandroid/tizen/vnc/x11: limit visual log screenshots

in fmbtgti.enableVisualLog(..., screenshotLimit=n)
the screenshotLimit parameter defines how many unreferenced
screenshot files will be kept on disk during test run.
This does not affect screenshot files with highlighted
content (taps, detected bitmaps and OCR texts). By default
there is no limit.
Merge remote-tracking branch 'devel/devel'
fmbtgti: added setScreenshotSubdir()

setScreenshotSubdir(strftime-format-string) enables saving
screenshot files to subdirectories under screenshotDir().
Enables avoiding thousands of files in the same directory at
the end of a test run.
fmbtgti: added screenshot limit and archive method

setScreenshotLimit() defines the maximum number of unused screenshots
that are stored to disk as is. If the limit is exceeded, screenshots
that are already stored to disk will be archived. Currently two archive
methods are supported: removing and resizing.
setScreenshotArchiveMethod() is provided for configuring the method.

This breaks API on an earlier devel version: screenshotLimit is no
more a parameter of enableVisualLog. (Archiving screenshots is needed
also without visual logging.)
Merge remote-tracking branch '01org/devel'