Document completion shortcuts

- Dot-completion templates that have snippets that can be inserted now tell you (took me quite a while to figure this one out, don't think many ppl know about it):

![](http://i.imgur.com/KTyFnA1.png)

- Changed the "Help" shortuct from `F1` to `Ctrl+F1` to fix the conflict with "show calltip details".
- Shortened calltips now mention the `F1` shortcut (another little-known shortcut):

![](http://i.imgur.com/AjA6ALY.png)

Adding this  `ShowDetailsCondition` delegate to `MemberItem` isn't right.

You should define a new `SnipperItem` class extending `MemberItem` (only for `Template` members) and that would override `get Description` to test for `HasSnippet` and adding the hint in this case.