Add TCEOVERFLOW error code
Add truncation/overflow checks & reporting

This is based on ed97cf64d89979ead63c662d42d19f7d0bfaee09, but somewhat
less agressive (no `abort` calls).

Original idea by Bastiaan Stougie <bstougie@b-virtual.org>.
TCHDB: Fixup 32bit overflows

This is an attempt to fix 32bit overflows in TCHDB in order to squash
ARAKOON-373.

Based on 8fd64af678c613c8f035ecf8a3276c6cf0aea370.

Original patch by Bastiaan Stougie <bstougie@b-virtual.org>.
Merge pull request #2 from Incubaid/ARAKOON-373

Implement 32/64-bit overflow checks (errors) & fixes