* module/rnrs/base.scm (log): now takes a base argument, using the
change of base formula for logs.
* test-suite/tests/r6rs-base.test ("log (2nd arg)"): Add test cases.
* module/rnrs/base.scm (real-valued?, rational-valued?,
integer-valued?): Implement in compliance with R6RS.
* test-suite/tests/r6rs-base.test: Add test cases for
`real-valued?', `rational-valued?', and `integer-valued?'.
* NEWS: Add NEWS entries.
`for-each' and `map' implementations do not operate on lists and vectors
interchangeably.
* module/rnrs/base.scm (vector-for-each, vector-map): New functions.
* test-suite/Makefile.am: Add test-suite/tests/r6rs-base.test to SCM_TESTS.
* test-suite/tests/r6rs-base.test: New file.