ENH: adjust completion parser

- restrict to text between "^[Oo]ptions:" and "-help-full" to avoid
  potential issues when more text is introduced in the usage output.

bin/tools/foamCreateCompletionCache

@@ -147,7 +147,8 @@ HEADER
 #   -hostRoots    Advanced distributed run option
 #   -roots        Advanced distributed run option
 #
-# Terminate parsing on first appearance of -help-full.
+# Begin parsing after first appearance of "^[Oo]ptions:"
+# Terminate parsing on first appearance of "-help-full"
 # - options with '=' (eg, -mode=ugo) are not handled very well at all.
 # - alternatives (eg, -a, -all) are not handled nicely either,
 #   for these treat ',' like a space to catch the worst of them.
@@ -155,7 +156,8 @@ extractOptions()
 {
     local appName="$1"
     local helpText=$($appName -help-full 2>/dev/null | \
-        sed -ne 's/^ *//; /^$/d; /^[^-]/d; /^--/d; /^-help-man/d;' \
+        sed -ne '1,/^[Oo]ptions:/d' \
+            -e 's/^ *//; /^$/d; /^[^-]/d; /^--/d; /^-help-man/d;' \
             -e '/^-hostRoots /d; /^-roots /d;' \
             -e 'y/,/ /; s/=.*$/=/;' \
             -e '/^-[^ ]* </{ s/^\(-[^ ]* <\).*$/\1/; p; d }' \