default config file clobbered

[tox2ik]

to reproduce:

start with a ~/.config/twmn/twmn.conf containing

bounce=false
duration=333
#[main]

run the daemon

$  twmnd

expected behavior:

twmc is able to connect
config file is not altered

actual result:

twmc is able to connect
config file is replaced by default
twmd output contains:

Starting twmnd version 1.2
Creating default settings ... 

I don't like that the config file is nuked if it does not contain the [main] section.
You should fill in the "missing values" at runtime with defaults without writing over "my" config file!