return term freq per doc also
return the payloads
 make get document frequency configurable
make one parameter for all term statistics. Step 1: rename. next: write other statistics
return also the ttf
all statistics written. next: json
json works, next: separate bool for term and field stats
add bool for field statistic
refactor builder, method was way too long
more tests
cleanup imports
move config from data field to header
more test and fix write/read of request
format
fix tests
update doc
make sure no crash if int and long stats are negative