Column-ui will look for columns configuration in:
1. system-wide configuration:
/etc/topydo_columns.conf
2. user dir:
~/.topydo_columns
~/.config/topydo/columns
3. current dir:
.topydo_columns
topydo_columns.conf
topydo_columns.ini
Each column should have its own INI style config section:
[FooBar]
title = Foo
filterexpr = Bar
sortexpr = desc:prio
show_all = 1
If any column option is missing, default value will be used.