Remove $FreeBSD$: one-line .c pattern

Remove /^[\s*]*__FBSDID\("\$FreeBSD\$"\);?\s*\n/

tools: minor spelling fixes.

Mostly comments but also some user-visible strings.

MFC after: 2 weeks

Add a `fix' for another whitespace bug.

If the sentence starts with a multiple of eight spaces, the sentence
should in almost all practical cases have started with tabs instead.
Replace these spaces by tabs.

Add fixwhite(1).

This small utility can be used to `sanitize' the whitespace in source
code. It does the following things:

Global:
- Remove empty lines at the beginning and the end of a file.
- Merge successive empty lines into a single empty line.

Per-line:
- Remove trailing whitespace.
- Merge spaces preceeding tabs into the tabs.

It operated on stdin/stdout. This means that if you use vi(1), you can
just run :%!fixwhite to reorganize the file.