is in accordance with the information provided at
ftp://ftp.cs.berkeley.edu/pub/4bsd/README.Impt.License.Change
Also add $FreeBSD$ to a few files to keep svn happy.
Discussed with: imp, rwatson
match text; it also doesn't warn() for files which can't be opened. Remove
global variables. Use bool. fopen(3) the files instead of freopen(3)ing stdin.
Add some constness to avoid some warnings.
Remove use register keyword.
Deal with missing/unneeded extern/prototypes.
Some minor type changes/casts to avoid warnings.
Reviewed by: md5
Implement -s option
Keep going if a file is not found
Append ':' to printed filenames
Include backslash in terminal characters
Make exit status dependent on a match having been found
Revise manpage accordingly