Speed improvement for opening the movies library

On all but the first time of opening the movies library, the CFileItemList
is built using CArchive. A large proportion of the time taken to do this is
actually spent in CVideoInfoTag::Archive() where it calls
CScraperUrl::Parse() and CFanart::Unpack(). Unless I've overlooked something,
these calls are unnecessary - the XML parsing they do is not performed the
first time the movies library is opened (when instead the virtual directory
videodb://movies/titles/ is enumerated using a database query). Also, the
Parse() method is called again when you do something like open the Movie
Information window, irrespective of whether it was called when the library
was opened.

Also note, it is unusual for any implementation of IArchivable::Archive() to
do anything other than read or write a data member from/to a CArchive, so
these calls to Parse() and Unpack() feel like an anomaly.

Additionally, inserted a call to std::vector::reserve() before reading the
cast list, because it was an obvious speed win.

Here are some benchmarks for the function CGUIMediaWindow::GetDirectory()
on a library of 600 movies, running on a Raspberry Pi:
* First call (before or after):    3.4 seconds
* Subsequent calls (before patch): 7.3 seconds
* Subsequent calls (after patch):  2.9 seconds
ffmpeg: add swr_set_compensation to interface
ActiveAE: use swr_set_compensation for changing resample ratio
Merge pull request #3233 from bavison/faster_videoinfotag_archive

Speed improvement for opening the movies library
[cosmetic] rename non-member var
[Fix][StringUtils] Prevent infinite loop or crash.

Example:

  std::string rep = "1";
  StringUtils::Replace(rep,"",""); //infinite loop
  StringUtils::Replace(rep,"","1"); //crash std::bad_alloc
Merge pull request #3255 from ace20022/fix_replace

[Fix][StringUtils] Prevent infinite loop or crash.
Merge pull request #3240 from FernetMenta/aefixes

ActiveAE: fix setting resample ratio
[externalffmpeg/osx/ios] - fix compile after 429ce9bc69cdee21d3f3be23c1f7147f25b42db6
jsonrpc: fix Playlist.Add/Insert not working with "directory" (fixes #14578)
jsonrpc: cosmetics in JSON schema