More directory tests

Confirming that the changes to path handling didn't break anything.
`~/` works locally, but I'm not sure how to actually include that as a test.

tests/links/more_dirs.sby

@@ -0,0 +1,17 @@
+[tasks]
+link
+copy
+
+[options]
+mode prep
+
+[engines]
+btor btormc
+
+[script]
+read -noverific
+script dir/script.ys
+
+[files]
+here/dir ${WORKDIR}/../dir
+a/b/c.v prv32fmcmp.v

tests/links/more_dirs.sh

@@ -0,0 +1,10 @@
+#!/bin/bash
+set -e
+if [[ $TASK == link ]]; then
+    flags="--setup --link"
+else
+    flags="--setup"
+fi
+python3 $SBY_MAIN -f $SBY_FILE $TASK $flags
+
+test -e ${WORKDIR}/src/here/dir -a -e ${WORKDIR}/src/a/b/c.v