Test the whole string in dbuf_test

not just the first 8 or 4 bytes.
Adjust unit test C indentation

to look like the rest of the Droplet library code.
Fix compile warnings in unit tests.
Comment out code more sensibly

Using a single #if 0 #endif pair not a /* */ pair per line.
Fix compile warnings in the SWIFT backend
Unit test runner valgrinds itself

if /usr/bin/valgrind is available
Fix memleak in dpl_task_pool_destroy()

Discovered when running unit tests under valgrind.
Git-ignore the unit test executable
Fix memleaks in unit tests

These are all bugs in the tests themselves.
Fix spurious timeout in taskpool test

when run under valgrind.
Fix memleak in taskpool test
Avoid emitting anything to stdout

by using fmemopen() to print to a memory buffer instead.  This also
allows us to test that the values printed are correct.
Workaround bugs in check.h assert macros
Use <check.h> comparison assert macros
Use pseudorandom bytes in ntinydb test

instead of pointlessly draining large amounts of entropy from /dev/urandom
Don't do unbounded sprintf() in SWIFT code

because that's just a security issue.
Merge pull request #157 from gnb/docs2

Docs2