Update README with more compatible test setup

Author: ddennedy

.gitignore

@@ -68,4 +68,4 @@ out
 src/swig/ruby/markdown/
 CMakeLists.txt.user
 .cache/
-
+*_export.h 

README.md

@@ -37,7 +37,7 @@ Testing
 To execute the mlt tools without installation, or to test a new version
 on a system with an already installed mlt version, you should run:
 
-    . setenv
+    source setenv
 
 NB: This applies to your current shell only and it assumes a bash or
 regular bourne shell is in use.