improve sizing on esi fit import browser

[AaronOpfer]

On my machine, using the ESI import feature and clicking "Fetch Fits" gives the appearance of nothing happening. Turns out, this was because by default the tree on the left-hand side of the window has zero width by default and the parent window needs to be resized to see the fits. Fix this by setting a minimum size for the fitting browser tree and increase the default window size to compensate.

[DarkFenX]

How does it look for you pre-fix?

Please provide screenshot, as well as some extra info - OS, pyfa version, UI scaling factor if non-100%, screen resolution. Include dependency versions as well if they do not match those listed in requirements.txt.

I might need this info to see if there's better fix for the issue or not. On my rig, left column is shown.

[AaronOpfer]

Debian Stable, pyfa is master 1d8c9d2, UI scaling factor I think is 125% but I'm not sure. 2560x1440 resolution.

pip freeze

asn1crypto==0.24.0
beautifulsoup4==4.6.3
certifi==2018.10.15
cffi==1.11.5
chardet==3.0.4
cryptography==2.4.1
cycler==0.10.0
diskcache==3.1.0
filelock==3.0.10
idna==2.7
kiwisolver==1.0.1
Logbook==1.4.1
markdown2==2.3.6
matplotlib==3.0.2
numpy==1.15.4
packaging==18.0
pluggy==0.8.0
py==1.7.0
pycparser==2.19
pyparsing==2.3.0
Pypubsub==4.0.0
python-dateutil==2.7.5
PyYAML==3.13
requests==2.20.1
roman==3.1
six==1.11.0
snakeviz==2.0.0
SQLAlchemy==1.2.14
toml==0.10.0
tornado==6.0.2
tox==3.5.3
urllib3==1.24.1
virtualenv==16.1.0
wxPython==4.0.3

[DarkFenX]

Which DE and display server do you use? Fractional scaling factors are experimental as far as i know. They might affect that. Also, wx 4.0.3 might too.

This is how it looks on my debian testing rig (wx 4.0.4, wayland, gnome, 100% scale) before the fix:

[DarkFenX]

That said, I do not see anything bad in making the window a little bigger, merging.