Fix inclusive_scan example which uses non-existent init parameter.

Reported by Github user tunaaa

Fixes #323
Merge pull request #324 from jaredhoberock/issue-323

Fix inclusive_scan example which uses non-existent init parameter.
Add device_vector::operator=(const host_vector &) (and vice versa) to
eliminate unintentional temporary copies during assignment.

Reported by Shiyin Kang

Fixes #325
Merge pull request #326 from jaredhoberock/issue-325

Add device_vector::operator=(const host_vector &) (and vice versa) to
Eliminate race in merge_subtiles_by_key_closure.

Fixes #327
Merge pull request #328 from jaredhoberock/merge_sort

Eliminate race in merge_subtiles_by_key_closure.
Document scatter & scatter_if's preconditions.

Fixes #308
Eliminate race in thrust::system::cuda::detail::merge_n

Fixes #329
Merge pull request #330 from jaredhoberock/merge

Eliminate race in thrust::system::cuda::detail::merge_n
Document thrust::malloc.
Document thrust::free.
Puth thrust::malloc and thrust::free in the same documentation groups as device_malloc and device_free, respectively.
Document get_temporary_buffer & return_temporary_buffer.
Removed extra semicolon from word_count example

Removed extra semicolon from word_count example
Merge pull request #332 from souravzzz/patch-1

Removed extra semicolon from word_count example
Fix error in gather_if's documentation

Reported by Björn Hegstam
DOC: Typo in device_reference example.
Merge pull request #333 from johntyree/patch-1

DOC: Typo in device_reference example.
Document the policy-based versions of for_each & for_each_n.
Document the policy-based versions of thrust::adjacent_difference
Document the policy-based versions of thrust::copy, thrust::copy_n, and
thrust::copy_if