Setting min/max srate equal to srate if they are unspecified.

Setting min/max srate equal to srate if they are unspecified. If only one of min/max-srate is specified, the other value will default to srate. If srate is unspecified, it will default to 1024 Hz.

Designed to addres @meg.millhouse request:

if you're passing it a cwb trigger list, if you specify srate in the ini file but not minsrate/maxsrate it defaults to 1024 instead of  what you feed srate.  Would it be possible to change that? Like would it break things if specifying min/max srate  was optional?

The same logic is also applied to seglen, window and flow.

@meg.millhouse please take a look and approve if it matches what you need. Note that the diff might look weird due to me moving some things around.