Trivial change to solution file, removes reference to nonexistent file.
Resolve #15 - alter namespace of IEnumerableExtensions to CSF.Collections

This functionality shouldn't have been in the root namespace in the first place.

* Functionality and tests still exist for the old namespace but are marked
  obsolete.  In the next major version they may be removed.

* Tests added for functionality in new namespace.
Resolve #10 - fix NIE in AssemblyExtensions type.

This was a missing implementation, it has now been provided and tests written
for it.
Resolve #14 - extend functionality of IEnumerableExtensions

This adds functionality for a generic-typed IEnumerable<T> to be turned into a
separated string, including using a 'selector' function.  For example:

IEnumerable<DateTime> test = // Create a DateTime collection
test.ToSeparatedString(", ", x => x.Year);

This would return a separated string containing only the years, and not the
whole DateTime instance.

* Some trivial refactoring of the IEnumerable extensions, but no
  non-backwards-compatible changes to the public API.
Resolve #12 - add "to readonly list" functionality for ILists.

This is new functionality that copies a mutable list as a readonly list.