libproj not correctly referenced when installing on Mac

[SZanlongo]

Bug Description

When installing flow on Mac, libproj is not correctly referenced.

Bug Reproduce

1. Install flow / sumo following instructions
2. sumo --version raises error message: dyld: Library not loaded.

Appears to have been resolved by creating a symbolic link between /usr/local/opt/proj/libproj CURRENT VERSION and /usr/local/opt/proj/libproj EXPECTED VERSION.

[davebiagioni]

I'll piggyback on this with a little more specific info about the error and the fix.

System info:

$ sw_vers
ProductName:	Mac OS X
ProductVersion:	10.15.3
BuildVersion:	19D76

Error:

$ sumo --version
dyld: Library not loaded: /usr/local/opt/proj/lib/libproj.15.dylib
  Referenced from: /Users/$USER/sumo_binaries/bin/sumo
  Reason: image not found
Abort trap: 6

So it wants version 15 of this library, but I can see that 19 is installed:

$ ls /usr/local/opt/proj/lib/
libproj.19.dylib libproj.a        libproj.dylib    libproj.la       pkgconfig

Solution was to create a symbolic link to the expected version:

$ ln -s /usr/local/opt/proj/lib/libproj.19.dylib /usr/local/opt/proj/lib/libproj.15.dylib

Now:

$ sumo --version
Eclipse SUMO Version 1.1.0
 Build features: x86_64-apple-darwin18.6.0 GDAL GUI Python
 Copyright (C) 2001-2018 German Aerospace Center (DLR) and others; http://sumo.dlr.de

Eclipse SUMO Version 1.1.0 is part of SUMO.
This program and the accompanying materials
are made available under the terms of the Eclipse Public License v2.0
which accompanies this distribution, and is available at
http://www.eclipse.org/legal/epl-v20.html
SPDX-License-Identifier: EPL-2.0