Fix the arrangement of Fscan buttons

[alurban]

This PR fixes the arrangement of Fscan buttons so that they have 4 to a row, befitting their configuration in O3. It also includes one PEP-8 compliance fix.

cc @duncanmmacleod

[codecov]

Codecov Report

Merging #285 into master will not change coverage.
The diff coverage is 0%.

@@           Coverage Diff           @@
##           master     #285   +/-   ##
=======================================
  Coverage   38.88%   38.88%           
=======================================
  Files          47       47           
  Lines        7387     7387           
=======================================
  Hits         2872     2872           
  Misses       4515     4515

Flag	Coverage Δ
#Linux	38.88% <0%> (ø)	⬆️
#python35	38.88% <0%> (ø)	⬆️
#python36	38.88% <0%> (ø)	⬆️
#python37	38.88% <0%> (ø)	⬆️

Impacted Files	Coverage Δ
gwsumm/tabs/fscan.py	16.41% <0%> (ø)	⬆️

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