Strip declarations when compiling a block.

I.e. not only for LAMBDA.  Currently enabled for LET and LET*.
Add and export PUSHNEW.
Add and export DO-(ALL/EXTERNAL)-SYMBOLS.
Fix return value.
Add package tests.
Merge branch 'package-improvements' of https://github.com/Ferada/jscl into Ferada-package-improvements
Merge branch 'master' of github.com:davazp/jscl

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