This changes the vector<T> constructors which copy or initialize
data to take a queue argument used for performing the operations.
Previously they just took a context argument used to initialize the
buffer and then created a new command queue to use. This improves
performance by not requiring a new command queue and also fixes issues
when performing operations on a different command queue while the
vector was still being initialized.
This adds a simple inplace_merge() algorithm which merges
two contiguous sorted ranges in-place.
For now, the implementation simply copies the ranges to
two temporary vectors and calls merge().
