Backend API: provide path to profile directory

[GoogleCodeExporter]

At the moment, Enso is using the HOME environment variable to get the
user's home/profile directory - unfortunately, this doesn't exist in
Windows. Therefore, it needs to be delegated to the platform-specific backends.

My recommendations are as follows:

* On Linux (and probably OSX?): $HOME/.enso/
* On Windows: $APPDATA\Enso\

I suggest a Enso-specific sub-directory so that Enso doesn't pollute the
user's home directory. Plugins should be able to write to this directory -
saving settings, saving data related to learning, etc.

The backends will therefore need to implement a new provider interface, as
the existing ones don't fit with this functionality.

Original issue reported on code.google.com by unfocu...@gmail.com on 25 Mar 2008 at 10:32

[GoogleCodeExporter]

On Linux, the folder should be $HOME/.local/share/enso/ -- app-specific files 
should
go in .local these days.

Original comment by stuart.l...@gmail.com on 11 Jul 2008 at 2:14

[GoogleCodeExporter]

SCRIPTS_FOLDER_NAME is now defined in the community branch (which defines a 
folder
rather than a file): however, this should be moved somewhere into /platform/ 
(at the
moment it's hardcoded to the Linux version, ahem). Allow overriding with an
environment variable, but provide sensible defaults for each platform.

Original comment by stuart.l...@gmail.com on 15 Sep 2008 at 7:10