1. ctype.h defines digittoint(), isnumber() and ishexnmber(), yet
they are not documented in any of the manpages.
2. The ctype manpage references a non-existent manpage for
digittoint().
3. The isascii() manpage claims it is standards compliant, when
it isn't.
4. isblank() claims it is _not_ standards compliant, when it
is.
Fix by including the appropriate .Nm entries, and with a new digittoint.3
page.
PR: docs/26451
Submitted by: Adrian Filipi-Martin <adrian@ubergeeks.com>