Fixed a formerly unnoticed crash bug. If user selected a subset of the dependency files list, then clicked "Copy Selected Audio Into Project", it removed the selected dependency/dependencies, but then crashed on bad reference trying to delete the non-selected dependency/dependencies. This was due to a consistent misuse of wxHashMap::operator[] to check for the existence of a hash element. If you call it with a key that's not in the hash map, yes it returns NULL, the first time, but it creates an entry for that key. So if you test it again with the same key it returns a bad entry. Replaced it with a correct call to wxHashMap::count(). Leland had fixed one of these, but there were 4 more.
RemoveDependencies() always returned true, and was never checked, so made it return nothing.
More readability improvements.
Update header block.
Move declarations that aren't used elsewhere, from .h file. No need to expose them there, used only in this file.
Working on first part of bug 113 where moved/deleted file is allowed to be copied into project:
* Made class AliasedFile know whether its original file exists in specified location.
* Dependency dialog:
** Updated so message states some original files were moved/deleted, and what to do about it.
** Missing dependencies shown in red, italic text.
** Missing dependencies cannot be selected for copying into project.
* Fixed bug where deselecting all items did not disable "Copy Selected..." button.
FindDependencies always returns true, so removed return value and its handling.
Sundry readability improvements: var names, {} brackets usage consistency, indenting, clearer names, etc.
Get rid of vim/emacs declarations. Matt said they're unnecessary, ages ago.
