* eval.c (scm_badargsp, SCM_CEVAL): Replaced SCM_N?IMP by a more

* eval.c (scm_badargsp, SCM_CEVAL): Replaced SCM_N?IMP by a more
explicit predicate in some places.

(CHECK_EQVISH): Removed.

(SCM_CEVAL): Removed some uses of t.arg1 and proc as temporary
variables.  Removed side-effecting operations from conditions and
macro calls.  Introduced temporary variables for clarification.
Sorted if-else-if check for the type of the last form in a list by
frequency.  Avoided some unnecessary tail-recursion calls.