Fix test colorization
improved symbol printing
Merge branch 'print' of https://github.com/6502/jscl

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Add clarifing comment
Add ALPHA-CHAR-P. FIND and FIND-If work also on sequences
The reader will ignore expressiones prefixed with #+nil
Rewrite and simplify potential-number-p according to the spec rules.

The previous implementation failed with '+' and '-' as input.
Escape token also for the package prefix