Correctly delete selected text starting w/ space

[kbrose]

Fixes #96

If text was selected that also triggered the check for the following:

    // If cursor has whitespace to the right, followed by non-whitespace,
    // and also has non-whitespace to the left, then trim the whitespace to the right
    // of the cursor. E.g. in cases like "def f(x,| y):"

then an invalid edit would be constructed and thus rejected, so no edits would be made.