Updated copyright notices to include the year 2018.
global: Replace o_stream_nfinish() with o_stream_finish() whenever possible
lib: test-ostream-* - Call o_stream_nfinish() after uncorking
global: use i_rand_limit() and i_rand_minmax() when possible
global: Replace random_fill_weak with random_fill They are now the same thing
global: Replace rand with i_rand
lib: Created basic test suite for ostream-buffer.