Remove stray numpy import (#185)

NumPy was being imported in the template code (not the template output) for
apparently no reason. This was causing problems when cross-compiling, where
NumPy is only available for the target platform.

Signed-off-by: Ben Wolsieffer <benwolsieffer@gmail.com>

Author: lopsided98

rosidl_generator_py/resource/_msg.py.em

@@ -30,7 +30,6 @@ from rosidl_parser.definition import UNSIGNED_INTEGER_TYPES
 @# Collect necessary import statements for all members
 @{
 from collections import OrderedDict
-import numpy
 imports = OrderedDict()
 if message.structure.members:
     imports.setdefault(