glasgow macOS setup

1. Install Homebrew (https://brew.sh)
```
/usr/bin/ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"
```

2. Install python3.7
```
brew install python3
```

3. Install opensource FPGA toolchain
```
brew tap ktemkin/oss-fpga
brew install --HEAD icestorm yosys nextpnr-ice40
```

4. Install sdcc
```
brew install sdcc
```

5. Install required python packages
```
python3.7 -m pip install setuptools libusb1 aiohttp bitarray crcmod
``` 

6. Obtain the source code:
```
git clone https://github.com/GlasgowEmbedded/Glasgow
cd Glasgow
git submodule update --init vendor/libfx2
```

7. Install the dependencies and the binaries for the current user
```
cd software
python3.7 setup.py develop --user
```

The binaries are placed in $HOME/Library/Python/3.7/bin/glasgow, so be sure to add that directory to the PATH environment variable; after this, you can run glasgow from a terminal. Instead of adjusting PATH it is also possible to use `python3.7 -m glasgow.cli` or create a symlink to `/usr/local/bin/glasgow`.

To update the source code, do:
```
cd Glasgow
git pull
cd software
python3.7 setup.py build_ext
```

Troubleshooting
Q: I have an error `E: __main__: device not found`
A: This can happen when glasgow is called very first time, just run glasgow one more time and issue will magically dissapear