add third_party dir to git ignores
fix sgvectors' refcount - to 0 -> ref -> 1 upon init
Merge pull request #1419 from votjakovr/develop

Add third_party dir to git ignores
Fix spinlock detection with clang
Add the right pthread library flag to the linking flags
Fix location of try_compile of spinlock test
Write suport for opertor new and delete using Jemalloc
Now comparing vector to clone (was: vector to itself)
fix doc Makefile
Merge pull request #1426 from tklein23/fix_sparse_vector_unit_test

Fixed SGVectorTest: Now comparing vector to clone (was: vector to itself)