#136 Initial folding for selected folding blocks

[fkite]

A way to set initial folding for selected folding blocks, overriding global editor setting "Fold all on file open". For example, folding block started with "//{-" instead of "//{" should be folded on load, regardless of "Fold all..." setting.

PS Also, it would be convenient to use bang to highlight the first line of a folding block, like "//!{", but i'm too scared to open a ticket for that.