Generalize +jump/online #140

+ Now uses selection if region is active. Prompts for the query
  otherwise, with the thing at point as the initial input.
+ On first use, prompts for provider. On consecutive uses, reuses
  previous provider. If universal argument is supplied, force the prompt
  to appear.

modules/feature/jump/config.el

@@ -14,7 +14,7 @@
 ;; in the future. When xref can't be depended on it will fall back to
 ;; `dumb-jump' to find what you want.
 
-(defvar +jump-search-url-alist
+(defvar +jump-search-provider-alist
   '(("Google"        . "https://google.com/search?q=%s")
     ("DuckDuckGo"    . "https://duckduckgo.com/?q=%s")
     ("DevDocs.io"    . "http://devdocs.io/#q=%s")