Add try_open parameter to goto_selected_file()

To do not hardcode check for :grep menu.
Show goto_selected_file() errors for all menus

Not just for :locate and user's menu.
Explicitly pass file path to goto_selected_file()

No need to pass pointer to whole menu structure.
Extract modes/menu.c:pass_combination_to_khandler()

Gives menu-specific keyboard routine to process the shortcut.
Pass "gf" in menu mode to menus implementation

Won't work by default.
Try harder to open file for editing

Don't fail if file number is not found, just open file as it is.
Update menu's khandler description
Add general function to handle file list keys
Enable filelist keys for :find/:locate/%M menus

 - "gf"
 - "e"
Document new "gf" and "e" keys in several menus

More precisely in:
 - :find
 - :locate
 - user menu with navigation (%M macro)
Rename dirsta{s,c}k_menu.{h,c}

A typo.
Change keys type of khandlers to const wchar_t[]

Was wchar_t[] for some reason.
Introduce khandler response enumeration

That < 0, > 0 and = 0 thing is not the best thing to do.
Merge branch 'better-menu-navigation'

Add "gf" (go to file) and "e" (open in editor) keys to :find, :locate
and user menu with navigation (%M macro).