Add ability to use DUPLICATI__FILTER in after script about duplicati

[ts678]

Forum discussion is here. It's not clear if this was an oversight.
A casual reading of the example script (ignoring context) would make one think it should be in both scripts, as is LOCALPATH.

duplicati/Duplicati/Library/Modules/Builtin/run-script-example.bat

Lines 70 to 84 in 23065d4

	REM Filters are supplied in the DUPLICATI__FILTER variable.
	REM The variable contains all filters supplied with --include and --exclude,
	REM combined into a single string, separated with semicolon (;).
	REM Filters set with --include will be prefixed with a plus (+),
	REM and filters set with --exclude will be prefixed with a minus (-).
	REM
	REM Example:
	REM --include=*.txt --exclude=[.*\.abc] --include=*
	REM
	REM Will be encoded as:
	REM DUPLICATI__FILTER=+*.txt;-[.*\.abc];+*
	REM
	REM You can set the filters by writing --filter=<new filter> to stdout.
	REM You may want to append to the existing filter like this:
	REM echo "--filter=+*.123;%DUPLICATI__FILTER%;-*.xyz"

I need it as I want to backup this filters.

Workaround can get it in the before script.

[Jojo-1000]

The cause is that a special "filter" option is created before calling the modules, to allow them to change the filters. Before running the backup, it is removed to prevent side-effects.

duplicati/Duplicati/Library/Main/Controller.cs

Lines 626 to 628 in 8e25c6e

	// Make the filter read-n-write able in the generic modules
	var pristinefilter = string.Join(System.IO.Path.PathSeparator.ToString(), FilterExpression.Serialize(filter));
	m_options.RawOptions["filter"] = pristinefilter;

To get the information back in the after script, this would need to be repeated. Probably noone saw the need for that