Replace Fastfoo's misc.expand_tilde with own

... as it's going away from Fastfoo pretty soon.

src/libexec/saturnin-ln

@@ -2,7 +2,6 @@
 
 . $(ffoom path)
 
-ffoo import misc
 ffoo import pretty
 
 DEFAULT_TARGET=$HOME
@@ -25,6 +24,30 @@ usage() {
     usage_is "[-f|--force] [-t|--target TARGET] [SOURCE] [NAME]"
 }
 
+expand_tilde() {
+    #
+    # Exchange "~" for home
+    #
+    perl -pe "s|^[[:space:]]*~|$HOME|"
+}
+
+maybe_relpath() {
+    local src="$1"
+    local dst="$2"
+    $TRY_RELPATH || { echo "$src"; return 0; }
+    {
+        echo 'import os.path'
+        echo 'import sys'
+        echo 'src, dst = sys.argv[1:]'
+        echo 'r = os.path.relpath(src, dst)'
+        echo 'a = os.path.abspath(src)'
+        echo 'if len(a) < len (r):'
+        echo '    print a'
+        echo 'else:'
+        echo '    print r'
+    } | python "$src" "$dst"
+}
+
 link() {
     local src=$1
     local dst=$2