Add image preview as supposed in #70

The idea of this is to add JavaScript code to the page which iterates over all posts and check whether there is text in the post that matches a certain pattern. This pattern would match
1.) A URL prefixed with ! which is present anywhere in the post -> regex: "/!(http[^\s]+)/gi"
2.) A valid markdown image syntax like ![alternative text](http://my.url/great-image.gif) -> regex: "/!\[(.+)\]\((http[^\s]+)\)/gi"
If a matching text is found, the code will append an <img> tag to the post to render the (potential) image
restructured internals

constants at the top, utility functions at the bottom (function hoisting
FTW - though JSLint doesn't like it)

in the process, fixed misleading variable name (`s/Name//`)
fixed stylistic compliance

* explicit variables (avoiding nested jQuery calls)
* explicit function signatures (even when unused, for readability)
* line continuations (chaining operator)
* consistent use of quotes (single quotes only for embedding doubles)
* whitespace, natch
avoided duplicate event handlers

note the inline comment: I'm not sure why an event handler is required
in the first place if we're calling `focusField` directly anyway

(can't currently test this, so flying blind here)
fix #56  Entry form doesn't allow more than 140 chars

The solution allows to put more than 140 characters in the input field. The counter will count down to 0 and when it switches to negative values, the submit button is disabled so the input cannot be submitted. At the same time the "ENTER" hotkey on the input field is automatically disabled so the form can neither be submitted by pressing "ENTER".

The submit functionality is enabled again when the counter is back to 0 chars ore more.
added idea files to gitignore
bugfixes

- applied what I learned from FND regarding attribute stitching -> div.new-reply
- fixed broken unbind of focus event handler
- fixed "bad selector" from ".update form" to "form.reply-form"
#73 show only one "reply-form" at a time

A click on a post brings up a new "reply-to" input field. If another post is clicked, the previous "reply-form" should be closed first
fixed #78 duplicate ids for "text" field

After we fixed the first step of #73, there can only be a single "reply-form" on a page at a time. Therefore giving this reply-form's input field a unique id (different from the "entry-form") should fix the duplicate id issue.
Merge pull request #77 from aheusingfeld/master

Suggestions for #70 and #56