Replace misleading 'variables' concept ('tokens' seems better)

src/include/build.sh

     #
     local ftype="$1"
     case $ftype in
-        MKIT_COMMON)    _expand_variables "vars" ;;
-        markdown)       _expand_includes | _expand_variables "vars" ;;
-        rpmstuff)       _expand_variables "vars" "rpmstuff:vars" ;;
+        MKIT_COMMON)    _expand_tokens "tokens" ;;
+        markdown)       _expand_includes | _expand_tokens "tokens" ;;
+        rpmstuff)       _expand_tokens "tokens" "rpmstuff:tokens" ;;
         *)              die "unknown file type: $ftype" ;;
     esac
 }
     '
 }
 
-_expand_variables() {
+_expand_tokens() {
     #
-    # Expand variables from sections $@
+    # Expand tokens from sections $@
     #
     local script=$(mktemp --tmpdir mkit-tmp.XXXXXXXXXX)
     local section varname varvalue
         echo "s|__MKIT_PROJ_VERSION__|$(semver)|g;"
         echo "s|__MKIT_SELF_VERSION__|$MKIT_VERSION|g;"
     } >> "$script"
-    perl -wp "$script" || die "_expand_variables failed"
+    perl -wp "$script" || die "_expand_tokens failed"
     rm "$script"
 }