Add missing options to help text and reformat

[ryandesign]

In #27 I submitted some minor corrections to the help text but more extensive editing is still needed. After that PR, the first help screen from README.md looks like this:

           Approximate Pattern Matching GREP -- Get Regular Expression
Usage:
AGREP [-#cdehi[a|#]klnprstvwxyABDGIRS] [-f patternfile] [-H dir] pattern [files]
-#  find matches with at most # errors     -A  always output filenames
-b  print byte offset of match
-c  output the number of matched records   -B  find best match to the pattern
-d  define record delimiter                -Dk deletion cost is k
-e  for use when pattern begins with -     -G  output the files with a match
-f  name of file containing patterns       -Ik insertion cost is k
-h  do not display file names              -Sk substitution cost is k
-i  case-insensitive search; ISO <> ASCII  -ia ISO chars mapped to lower ASCII
-i# digits-match-digits, letters-letters   -i0 case-sensitive search
-k  treat pattern literally - no meta-characters
-l  output the names of files that contain a match
-n  print line numbers of matches          -q  print buffer byte offsets
-p  supersequence search                   -CP 850|437 set codepage
-r  recurse subdirectories (UNIX style)    -s  silent
-t  for use when delimiter is at the end of records
-v  output those records without matches   -V[012345V] version / verbose more
-w  pattern has to match as a word: "win" will not match "wind"
-u  suppress record output                 -x  pattern must match a whole line
-y  suppress the prompt when used with -B best match option
@listfile  use the filenames in listfile                              <1>23456Q

• The -H option is mentioned in the one-line help but not in the detailed help.
• The -b, -i0, -q, -CP codepage, and -V[012345V] options are mentioned in the detailed help but not in the one-line help.
• The -g, -m, -o, -z, -L, -M, -O, and -P options are not documented anywhere in the help.
• The -R option mentioned in the one-line help does not appear to exist (but is requested in missing (greplike) recursion -R #15). (How is this different from the -r option?)
• The -d, -e, and -k options apparently require an argument which the help does not make obvious. (Compare with how the -f option is documented in the one-line help.)
• The detailed help would be easier to navigate if it were sorted alphabetically by option (either case-sensitively or case-insensitively). It is currently somewhat alphabetical though with many deviations.
• The detailed help would be easier to read if it were arranged either in a single column (my preference) or two columns (if compactness is valued more highly than legibility). The current mix of sometimes one-column and sometimes two-column, varying by line, requires more effort to understand.

If you don't want to fix this yourself, I or someone else might be able to submit a PR if you could describe the undocumented options and indicate which of the various alternatives you prefer.