Added PXMC submodule accidentally deleted by Filip

See the commit f3ca0058b0794b97971e4a35b0e9ecf78b62b79a

diff --git a/src/pxmc b/src/pxmc
new file mode 160000 (submodule)
index 0000000..aa4e62d
--- /dev/null
+++ b/src/pxmc
@@ -0,0 +1 @@
+Subproject commit aa4e62d35130d1a5215a91d988a97bfe0e8f1056