Produces less noisy change objects when pressing enter.

It now focuses the new editor only if the textarea argument
currently has focus.

Closes #714

Closes #716

(scrollEditorIntoView)

Page-up would sometimes scroll all the way to the top even
though it shouldn't, because of a poorly chosen check in coordsChar.

The new check should no longer get false positives.

This allows client code to find out which part of the document
is currently being shown.

This reverts commit b1431bd1.

I pushed it by accident.

Makes tests pass on IE, FF, and Opera again.

Apparently, toUpperCase isn't all that standards, and ß.toUpperCase()
produces SS on Webkit, ß on other browsers.

Also worked around some crumminess in the way IE7 reports clientWidth.

Issue #697

This fixes the problem where the tabs interfere with other text when only
a single character wide.

Issue #673

In non-wrapping mode

It was creating a StringStream with a default tabSize.

This is easier to work with than the child/sibling pointer following
that was needed to get the elements out.

Also rename function createElement to elt, and make it possible to
pass an array of child nodes.

See 25f7d89f

Closes #709

Closes #708

The old solution made clicking on tabs (and other wide characters) always
put the cursor *before* them, even when clicking near their right.

Closes #703

Hide it by overlaying it with our fake scrollbar. Remove explicit wheel handling
for reasons of being extremely hard to get right.

Issue #694

Issue #698

Issue #698

And move browser detection up in the codemirror.js file, to prevent
further instances of 'use sniffing before actually doing it' bugs.