Get the environment propagated to scons forked childs, and correct the dicom plugin about
a typedef of size_t that failed at least on x86_64-linux.

diff --git a/SConstruct b/SConstruct
index 9e752d6..f93f27f 100644
--- a/SConstruct
+++ b/SConstruct
@@ -9,13 +9,7 @@ else:
 
 commit_id = os.popen('git rev-parse HEAD').read().replace('\n','')
 
-env = Environment(LIBPATH=[],
-                  CPPFLAGS = cppflags + ['-Wno-deprecated-declarations',
-                                         '-Wno-reorder',
-                                         '-Wno-unused-but-set-variable',
-                                         '-Wno-unused-function'],
-                  CXXFLAGS=['-std=c++1y']
-                  )
+env = Environment(ENV = os.environ)
 
 env['SBOX'] = False
 env['COMMITIDSHORT'] = commit_id[0:6]