[MLBEDSW-297] Setup and run on Microsoft Windows

Various updates to make vela run and produce identical output on
Microsoft Windows.
* Fixed overflow errors
* Fixed compile warnings
* Avoid problematic numpy version
* Updated README.md

Signed-off-by: Fredrik Svedberg <Fredrik.Svedberg@arm.com>
Change-Id: Ie48c63a92a00c81b3247d07f05b75d881319ddbb
diff --git a/setup.py b/setup.py
index 805062b..bb2e8a0 100644
--- a/setup.py
+++ b/setup.py
@@ -76,7 +76,12 @@
     keywords=["ethos-u", "vela compiler", "tflite", "npu"],
     packages=find_namespace_packages(include=["ethosu.*"]),
     python_requires="~=3.6",  # We support only 3.6+
-    install_requires=["flatbuffers==1.11.0", "numpy>=1.16.6", "lxml>=4.5.1"],
+    install_requires=[
+        "flatbuffers==1.11.0",
+        "numpy>=1.16.6",
+        "numpy>=1.16.6,<1.19.4 ; platform_system=='Windows'",
+        "lxml>=4.5.1",
+    ],
     entry_points={"console_scripts": ["vela = ethosu.vela.vela:main"]},
     ext_modules=[mlw_module, tensor_allocator_module],
     setup_requires=["setuptools_scm"],