* Support for highlighting all search matches (hlsearch)
hlsearch is implemented efficiently using the buffer's line array,
somewhat similarly to the syntax highlighting.
Unlike the syntax highlighter which highlights the entire file,
hlsearch searches for matches for the displayed lines only.
Matches are searched when the given line is displayed first time
or after it was modified. Otherwise the previously found matches
are used.
* Add UnhighlightSearch action
and add it to the list of actions triggered by Esc key by default.
* Add comment explaining the purpose of search map
* Add hlsearch colors to colorschemes
Mostly just copied from the corresponding original (mostly vim) colorschemes.
* Highlight matches during/after replace as well
As a side effect it also changes the last search value, i.e. affects FindNext
and FindPrevious, but it's probably fine. In vim it works the same way.
* Improve hlsearch option description
* Adds command "tabmove ±n", for better tab management
* Added tabmove to help:commands
* Replace uses of util.Min, util.Max with util.Clamp
Browsing code and discovered `util.Clamp`, ideal for this section of my code
* oops, missed an arg
* Typo, again
See https://golang.org/pkg/regexp/syntax/ for the
supported syntax. Here are some examples:
```
replace "(foo)" "$1-bar"
replace "(foo)" "${1}-bar"
replace "(?P<group>foo)" "$group-bar"
replace "(?P<group>foo)" "$group-bar"
replace "(?P<key>\w+):\s+(?P<value>\w+)$" "$key=$value"
```
Closes#1115
The autosave option is now specified as an integer, which denotes
the number of seconds to wait between saving the file. If the option
is 0, then autosaving is disabled. If the option is given by the user
as a boolean, it will be converted to 8 if true, and 0 if false.
Fixes#1479
With the new backup option, the autosave option is no longer useful.
Since it never really worked well in the first place, it has been
removed.
Closes#1420
