Save gutter images and folding dots with transparent background

This makes them conform to the informal template image format which is usable as-is as a CoreGraphics image mask.
Skip explicitly creating a CoreGraphics image mask
Use CGImageRelease instead of CFRelease
Add warning and error gutter view images
Use string instead of double for mate’s version number

With a double we can’t use version numbers like 2.8.1 or 2.10.
If updating mate requires admin privileges then ask user first

This way they should know what the password dialog is about.
Construct undefined text::range_t/pos_t if created from NULL_STR
Don’t change ninja goal for the mate target
Add API to remove (all) marks from (all) documents
Add support to mate protocol for setting and clearing marks
Add --set-mark/--clear-mark options to mate
Use text::pos_t as key when storing marks for closed documents

Since open documents only support a single position (not a range) it doesn’t make sense to use a range for closed documents.
Introduce constant for search mark identifier
Use public constant for bookmark identifier
Rework how marks are stored when there is no buffer_t
Preserve and adjust bookmarks when replacing in closed documents
Make countOfLeafs/Excluded a readonly property
Define excluded property for FFResultNode child nodes

This returns YES when all leafs are excluded.
Add ignored property to FFResultNode

When a group node is ignored then it report all its children as excluded regardless of their actual state. It is still possible to query the children for the real state.
Check if all matches are excluded before iterating through them