* Cache result of `verifyPresentTrackHeader()` instead of running the code
unnecassarily multiple times
* Do not tamper with existing/raw values by default to avoid
inconsistencies through rounding errors and possibly fix
https://github.com/Martchus/tageditor/issues/80
* Avoid conversions to double (depending on the time scale rounding errors
might still occur)
* Fix applying changes to symlinks so that the target is modified in any
case (and not just if a rewrite isn't necessary)
* Avoid using `std::rename` and `std::remove` because they might not work
under Windows when the path contains non-ASCII characters
* Simplify code, remove `isRelative()`
* Close or flush streams explicitely so writing is not
deferred
* to catch errors in the right place
* to avoid suppressing errors completely when writing
would be deferred to the destructor invocation
* Improve comments
This should fix all non-erros, leaving only warnings which
are indeed potential problems.
The following warnings should be safe to ignore:
* Conversions of various offsets from uint64 to
std::streamoff/int64 are safe because such offsets have
been obtained via tellg() and other functions
returning std::streamoff in the first place.
* It also works vice-versa since tellg() should not
return negative offsets with exceptions enabled.
* Conversions from char to unsigned char are also ok.
* Unused diag arguments can be ignored (those might be
useful later).
* Annotate all intended fallthoughs.
This also involves finally implementing
Mp4Track::makeTrack(). Mp4Track::makeSampleTable()
which would enable modifying stbl atom is still not
fully implemented yet, though.