add {java,python}_home()

Author: scivision

+stdlib/java_home.m

@@ -0,0 +1,13 @@
+%% JAVA_HOME get the JAVA_HOME environment variable
+
+function h = java_home()
+
+try
+  h = javaMethod("getProperty", "java.lang.System", "java.home");
+catch
+  h = '';
+end
+
+end
+
+%!assert(!isempty(java_home()))

+stdlib/python_home.m

@@ -0,0 +1,12 @@
+%% PYTHON_HOME tell the home directory of Python install
+
+function h = python_home()
+
+try
+  pe = pyenv();
+  h = pe.Home;
+catch
+  h = '';
+end
+
+end