CPU_ISSET may return any integer greater than 1, casting is needed.
Also, simplify the error checking with asserts.

Backtrace functions are GNU extensions.

Close #93

Timestamp last_borrow should only be updated when
the borrow does not succeed

Fix typo
Add and update some comments

Options parsing was not correctly removing "=values"

This option will make warnings to raise a DLB panic error

Function strstr cannot be used to remove tokens since it
may remove options that contain a substring of other option

Fix #89

- rebind also from the beginning
- preserve previous binding if possible
- do no set dirty flag if no thread needs rebinding