fix log file organization

supposed to be a named list of vectors (with print function?), if i remember right. appears to have become a 1-element list containing a list of vectors, at least for bayes models.

e.g., for an already-compiled model (with problems of its own, hence the interest in the log files):

``` r
rmname<-mm_name(type='bayes', pool_K600 = 'normal')
rmspecs<-specs(rmname)
> mm <- metab(rmspecs, data=dat)
> get_log(mm)[[1]]
### NA ###

### log ###

Click the Refresh button to see progress of the chains
starting worker pid=7812 on localhost:11192 at 13:59:24.196
starting worker pid=12180 on localhost:11192 at 13:59:24.424
starting worker pid=9080 on localhost:11192 at 13:59:24.672
starting worker pid=3832 on localhost:11192 at 13:59:24.891
no parameter K600_daily_pred; sampling not done
no parameter K600_daily_pred; sampling not done
no parameter K600_daily_pred; sampling not done
no parameter K600_daily_pred; sampling not done
> mm@log
$MCMC_All_Days
$MCMC_All_Days$
NULL

$MCMC_All_Days$log
[1] "Click the Refresh button to see progress of the chains" "starting worker pid=7812 on localhost:11192 at 13:59:24.196"
[3] "starting worker pid=12180 on localhost:11192 at 13:59:24.424" "starting worker pid=9080 on localhost:11192 at 13:59:24.672"
[5] "starting worker pid=3832 on localhost:11192 at 13:59:24.891" "no parameter K600_daily_pred; sampling not done"
[7] "no parameter K600_daily_pred; sampling not done" "no parameter K600_daily_pred; sampling not done"
[9] "no parameter K600_daily_pred; sampling not done"
```