table_stat(): Improve debugging
table_stat(): Improve debugging

1. Use "size_t" for hit/miss, since for long sentences "int" may wrap.
2. Fix using constant 31.
3. "max_chain_length" overflows the "chain_length" array if a pathological
chain length is encountered. Use another method to print this array.

ampli/link-grammar,ampli/link-grammar,linas/link-grammar,opencog/link-grammar,ampli/link-grammar,linas/link-grammar,opencog/link-grammar,ampli/link-grammar,linas/link-grammar,linas/link-grammar,opencog/link-grammar,linas/link-grammar,opencog/link-grammar,opencog/link-grammar,linas/link-grammar,linas/link-grammar,linas/link-grammar,ampli/link-grammar,ampli/link-grammar,opencog/link-grammar,opencog/link-grammar,linas/link-grammar,opencog/link-grammar,ampli/link-grammar,opencog/link-grammar,ampli/link-grammar,ampli/link-grammar