Set up autogenerating of static sheets
Minor adjustments for improved autogeneration of static sheets
Better screenshot alt text
Improved usability for variable legend

When a user would click on a `†i9` variable legend link, the page would jump to the legend. However the legend is contained within a (closed) accordion section, so the user would still not see the legend.

With this fix, the relevant accordion section is auto-expanded when a variable legend link is clicked.
Tidy up /remove redundant code

* Both the `$dir` as well as the `$min` variable will always be available (as long as setup-env.php is used and it always is), so no need to test with `isset()`
* top-menu links do need to use the `$dir` variable
* menu page will never be static, so image paths do not need the `$dir` variable
* footer page *will* be used in static pages, so about link should use the `$dir` variable

* Few more keywords for the meta keywords tag
* Clean up the page title
* No matter what spell check says, 'cheatsheet' is one word
* little tidying up of some html (indentations and end/div indicators)
Improve autogeneration php script

- Fixed: bug where page headers/footers were missing
- Fixed: files were not written to the correct subfolder
- Fixed: quiz files would be requested even if quiz not present

- Added: support for command line `verbose` option, defaults to 0 (=false)
- Added: counters for success/failure of file generation and pass the result as an exit code - this will work as long as there are less than 10 files to be written. If this would ever become more, the logic for the exit code will need to be revisited
- Added: the string replacements from the old 'correct paths in static files' script. Output from this can be silent or verbose for analysis purposes.
- Added: a check for fatal errors in the resulting generated files and provide appropriate error message
Add rationale for which PHP version warrants a static sheet
Yeah! Build script to autogenerate the static sheets for a multitude of PHP versions on one go ;-)

- Added: verbose command line options with three levels and adjusted php script to be able to deal with that:
	* 0 = only show summary
	* 1 = show info per PHP version requested
	* 2 = level 1 + show info on textual replacements made in resulting html source code