Fix symbol internalization in KEYWORD package

[kilianmh]

Replace keywords in defpackage :export and :shadow clauses with uninterned symbols. This avoids interning them in *package*, which should simplify autocompletion and may improve garbage collection.

[gefjon]

Can you get the symbol names in the import-from clause in the test package?

[kilianmh]

The symbol names in the test package :import-from clause are now also uninterned instead of keywords.

[kilianmh]

Reverting test package :IMPORT-FROM clause package name to KEYWORD, which should improve readability without unnecessary expansion of *PACKAGE*.

[kilianmh]

Summary:

Fix symbol internalization in KEYWORD package

• Replace KEYWORD (except library-names) with STRING in FLEXI-STREAMS.ASD
• Change DEFPACKAGE shadowed, imported, exported symbols to uninterned symbols

-> Reduction of KEYWORD package symbols by 54 when loading FLEXI-STREAMS -> Improved KEYWORD auto-correction