... To append files during recording or import, it doesn't depend on the
subclasses of BlockFile, instead taking a factory function to which it gives
the filename; and the choice of factory function is also lifted up through the
level of class Sequence which is just above DirManager.
This frees four files from dependency cycles, including DirManager.cpp but not
yet Sequence.cpp
... for wxString and wxArrayStringEx, holding file paths (absolute or relative,
directory or plain file); to be replaced later with different types
(not yet using std::vector, becase of some uses of wxArrayString::Index with
two arguments)
... Eliminate CreateFromCopy, add new one-step constructor instead.
It was wasteful to create a copy only to re-create the Sequence at once.
Sequence::Copy is a factory returning a unique_ptr.
Some error checks are removed, but there will be exceptions instead later.
... whenever they really describe the size of a buffer that fits in memory, or
of a block file (which is never now more than a megabyte and so could be fit in
memory all at once), or a part thereof.
... Define lots of operators for disambiguation, but they will go away after
all conversions from sampleCount to built-in numerical types are forced
to be explicit.
... for functions in final classes.
override is like const -- it's not necessary, but it helps the compiler to
catch mistakes.
There may be some overriding functions not explicitly declared virtual and I did
not identify such cases, in which I might also add override.
... Should have no effect on generated code, except perhaps some slight faster
virtual function calls. Mostly useful as documentation of design intent.
Tried to mark every one of our classes that inherits from another, or is a
base for others, or has abstract virtual functions, and a few others besides.
Create WaveTrackCache as a utility class but don't use it anywhere yet.
The possible minor performance problem with effects is fixed by changes
in WaveTrack::GetBestBlockSize().
