** check-in VERSION relative to its primary parent.
**
** The "-i" command-line option forces the use of the internal diff logic
** rather than any external diff program that might be configured using
** the "setting" command.  If no external diff program is configured, then
** the "-i" option is a no-op.  The "-i" option converts "gdiff" into "diff".
**
** The "-v" or "--verbose" option causes the complete text of added or
** deleted files to be displayed. -N and --new-file are aliases for
** verbose mode.
**
** The "--diff-binary" option enables or disables the inclusion of binary files
** when using an external diff program.
**
** The "--binary" option causes files matching the glob PATTERN to be treated
** as binary when considering if they should be used with external diff program.
** This option overrides the "binary-glob" setting.

**   --command PROG              External diff program. Overrides "diff-command"
**   --context|-c N              Use N lines of context
**   --diff-binary BOOL          Include binary files with external commands
**   --exec-abs-paths            Force absolute path names on external commands
**   --exec-rel-paths            Force relative path names on external commands
**   --from|-r VERSION           Select VERSION as source for the diff
**   --internal|-i               Use internal diff logic

**   --numstat                   Show only the number of lines delete and added
**   --side-by-side|-y           Side-by-side diff
**   --strip-trailing-cr         Strip trailing CR
**   --tclsh PATH                Tcl/Tk used for --tk (default: "tclsh")
**   --tk                        Launch a Tcl/Tk GUI for display
**   --to VERSION                Select VERSION as target for the diff
**   --undo                      Diff against the "undo" buffer
**   --unified                   Unified diff
**   -v|--verbose                Output complete text of added or deleted files
**   -N|--new-file               Alias for --verbose
**   -w|--ignore-all-space       Ignore white space when comparing lines
**   -W|--width N                Width of lines in side-by-side diff
**   -Z|--ignore-trailing-space  Ignore changes to end-of-line whitespace
*/
void diff_cmd(void){
  int isGDiff;               /* True for gdiff.  False for normal diff */
  int isInternDiff;          /* True for internal diff */