xls-report.py: add ability to specify arbitrary sheet properties
xls-report.py: removed image size and type from the list of other parameters.

Also, shrunk the corresponding column and the test name column.
Added to the test log parser a crude ability to detect non-implemented tests.
Made the crude ability less crude.
xls-report.py: Added an option to show per-pixel times
Merge pull request #1102 from SpecLad:xls-updates