Add helper functions to simplify operations in .mkit

src/include/mkit.sh

      || die "bad mkit.ini version: $their_ver does not match $MKIT_VERSION"
 }
 
+local_putb() {
+    #
+    # Make file $1 in $MKIT_LOCAL from stdin and mark as built
+    #
+    local fpath=$1
+    local_put "$fpath" && rec_built "$MKIT_LOCAL/$fpath"
+}
+
+local_put() {
+    #
+    # Make file $1 in $MKIT_LOCAL from stdin
+    #
+    local fpath="$MKIT_LOCAL/$1"
+    { mkdir -p "${fpath%/*}" && cat >"$fpath"; } \
+     || die "cannot write to local cache: $fpath"
+}
+
+local_get() {
+    #
+    # Read file $1 in $MKIT_LOCAL
+    #
+    local fpath="$MKIT_LOCAL/$1"
+    cat "$fpath" 2>/dev/null
+}
+
 mkit_init() {
     #
     # Do basic initialization
     _chkiniversion
 }
 
+rec_built() {
+    #
+    # Record file $1 for deletion on `clean`
+    #
+    local file=$1
+    mkdir -p "$MKIT_LOCAL"
+    echo "$file" >> "$MKIT_LOCAL/built.lst"
+}
+
 route() {
     #
     # Call correct function based on $1