Correct mbed export with multiple --source params

tools/project.py

@@ -4,7 +4,7 @@ supported IDEs or project structures.
 from __future__ import absolute_import, print_function
 import sys
 from os.path import (join, abspath, dirname, exists, basename, normpath,
-                     realpath, basename)
+                     realpath, relpath, basename)
 from os import remove
 ROOT = abspath(join(dirname(__file__), ".."))
 sys.path.insert(0, ROOT)
@@ -48,7 +48,7 @@ def setup_project(ide, target, program=None, source_dir=None, build=None, export
             project_name = TESTS[program]
         else:
             project_name = basename(normpath(realpath(source_dir[0])))
-        src_paths = source_dir
+        src_paths = {relpath(path, project_dir): [path] for path in source_dir}
         lib_paths = None
     else:
         test = Test(program)
@@ -254,7 +254,10 @@ def main():
             except (NotImplementedError, IOError, OSError):
                 pass
         for f in EXPORTERS.values()[0].CLEAN_FILES:
-            remove(f)
+            try:
+                remove(f)
+            except (IOError, OSError):
+                pass
     try:
         export(mcu, options.ide, build=options.build,
                src=options.source_dir, macros=options.macros,