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Merge pull request #15 from vicoapp/completion-as-you-type

Autocomplete as you type

There is now an option, "Complete as you type", that can be set in Editing options.
This means it can be set per-file-type, as well. It runs word-based completion as
currently triggered by C-N after two characters of a word have been typed.

This also implements completion so that typing while a completion popup comes
up also goes into the editor window, which did not used to happen.
Fixed initial position of window.
Fixed the alignment on font size changes.
Fixed indention with spaces instead of tabs.
Get Vico compiling on the 10.8 SDK and update Nu to 2.1.
Removed the 'a' flag in he completion commands.

Going forward, it will be ignored in favor of letting the app itself figure out
whether the completions needs to be above or below the current line.
Completion window now appears above if there is no room below.

The following things are now true:
(1) Vico displays at most enough completions to fill up half the screen,
    minus the current line of text and the prefix filter.
(1) If there is room to show all the available completions below the current
    line, Vico will show them below; otherwise, vico will show them above.

Note that because of (1), (2) can always happen.
Removed border from table view.
Removed .DS_Store so as to actually ignore it.
Added back the 3px offset to align the characters.
Fixed a bug that allowed the full screen height to be used for completions.
Removed an unncessary parameter; updated documentation.
Updated the selection rules.

The selected completion is the last element of the completions list
when the list is positioned above the cursor.
Some cleanup.
Changed the coloring of selected completions rows for legibility.
Changed some variable names to clarify meaning.

It was unclear that the bounding rect was for the prefix string.
Fixed a compilation error.
Renamed the color ranges to be semantic rather than visual.

Now the range that is grey is the "matchedRange" and the rest is the "completionRange",
in line with what they actually represent.
Clarified some comments.