Fix uvision group naming

The previous way of finding group names found the encompassing directory of each file. If the project is exported from the online compiler, this resulted in temporary folder names like tmpyKKWv_ showing up as group names.

I propose defaulting to the project name if the file is in the project root.

tools/export/exporters.py

@@ -121,8 +121,8 @@ class Exporter(object):
         def make_key(src):
             """turn a source file into it's group name"""
             key = os.path.basename(os.path.dirname(src))
-            if not key:
-                key = os.path.basename(os.path.normpath(self.export_dir))
+            if not key or relpath(key, self.export_dir) == '.':
+                key = self.project_name
             return key
 
         def grouped(sources):