COMMON: Fix regression in SineTable creation.

This is a regression from f4ba8a6485b097a8ef1e2004d1af127243f379f1. The
commit replaced the static cosine and sine tables with dynamically created
ones. In the process of that a copy&paste error happened which made the sine
table use the layout of the cosine table. This commit now changes the
dynamically created sine tables to conform to the layout of the previous
static tables.
COMMON: Save memory by allocating only required entries in Cosine-/SineTable.

The tables only contain (2^bitPrecision)/2 entries. The code allocated twice
as many entries previously.
COMMON: Try to document the SineTable/CosineTable table entries.
COMMON: Improve comment in CosineTable::CosineTable.

This commit changes the comment to use the same variable names as we do in the
code. Furthermore, it also makes the comment a bit easier to grasp.