[plt-scheme] drscheme extension to save an load a set of tabs

Hi Stephen,

> let me know what you think

Your first run looks good. Here are some thoughts:

Your icon looks good, but it is the wrong size. It should be 32x32. My
icon in DrSync looks, ok, but not good. I used pov-ray. I wish I had
an artist at my disposal.

I like your use of pack.ss. I had used shell scripts to package everything up.

I tested out the plugin, it works fine. Inevitably now people will
tell you "You should...". Here is my contribution :).

You could:
* Add scribble documentation.
* Put the buttons on the left near the file chooser/browser. Since you
are performing file operations, this is the logical place to find it.
* Upper-case the icon labels and remove the dash.
* When loading a project, don't re-load files that are already open.
* More clearly state your goals and vision of the plugin. Files
grouped into a project using this plugin, and the ability to browse
code dependencies using the module browser, seem to be complementary
features.
* Save more than 1 project

You could also:
* Use a different extension that .psp. That is associated to PSP image
files (on Windows atleast).
* Put the project file in the users home dir, use (find-system-path 'home-dir).
* I used the predicate for whether a tab has a file is to apply
file-path to the tab, rather than asking a tab for its filename and
checking if it exists.Tabs are created in a state where they aren't
associated with a file, the only way to associate them with a file is
by creating a new one or one that already exists (to the best of my
knowledge at least).
* A menu in the menubar might be a better place rather than buttons.
* The button icons don't show up for me, but I see them configured in
the button.

Best wishes,

Grant