* Fixed serios bug concerning non-unique ejdb2 indexes, details: htt…

…ps://github.com/Softmotions/ejdb/issues/291

  * Fixed potencial memory leak in `iwlist_create()` (iwarr.h)
  * Fixed wrong `iwulist_clear()` behaviour (iwarr.h)
  * Code cleanup
  * Added `iwulist_at2()` (iwarr.h)
  * Removed not needed assertion (iwstree.c)

 * Correct handling of EINTR, EAGAIN in read/write functions (unix.c)

  * Minor fixes on iwhmap

 * `pthread_barrierattr` shim for android API < 24

  * Added `iwsha256()` SHA-256 hash implementation (iwsha2.h)
  * Added single thread worker (iwstw.h)
  * Added `iwstree_clear()` (iwstree.h)

 * Added `iwulist_clear` (iwarr.h)

  * Added `RCIF` (basedefs.h)
  * Fix assertion error in `iwstree_remove()` (iwstree.h)
  * Allows zero key/value placeholders in `iwstree_iter_next()` (iwstree.h)
  * Added `iwstree_put_overwrite` (iwstree.h)
  * Added  iwstree iteration API (iwstree.h)
  * Added `iwpool_used_size` (iwpool.h)
  * Added `iwstree_int64_cmp` (iwstree.h)
  * Added `IW_DEPRECATED` (basedefs.h)

 * Fixed incorrect copying of cursor key data in `IWDB_COMPOUND_KEYS`…

… mode (iwkv.c)

  * Adde compound key example code (compoundkeys1.c)
  * Added `iwstree_visit` (iwstree.h)

 * Fixed errors found by PVS studio

 * Added IWULIST, IWLIST implementation (iwarr.h)

  * Added iwpool_split_string (iwpool.h)
  * Added iwpool_printf (iwpool.h)
  * Added iwpool_printf_split (iwpool.h)
  * Added iwxstr_shift (iwxstr.h)
  * Added `#define RCHECK` (basedefs.h)
  * Better error handling of `kh_put`

 * Fixed possible data corruption in `_fsm_blk_allocate_aligned_lw` (…

…iwfsmfile.c)

  * Better new SBLK blocks locality  (performance)

 * Implemented new compact and performant data storage format v2

  * Added WiredTiger v3.2.1 benchmarks
  * Added BerkeleyDB v5.3.28 benchmarks
  * Added TokyoCabinet v1.4.48 benchmarks

 * Added iwrc iwp_mkdirs(const char *path) (iwp.h)

  * Added uint32_t iwu_x31_u32_hash(const char *s) (iwutils.h)
  * Added iwu_replace() (iwutils.h)
  * Added RCGA macro definition
  * Removed IW_EXPORT iwrc iwkv_db_last_access_time(IWDB db, uint64_t *ts)
    for performance and simplicity reasons
  * Added `IW_ERROR_INVALID_VALUE`
  * Added iwstree - splay tree imlementation (iwstree.h)
  * Pointers allocated by iwpool are now 8-byte aligned