Added ProgressBarGUI class, and modified saveAs().

ProgressBar now shows properly for all files within the main sketch
folder, but not within sub-folders.

To Do:
1. Make ProgressBar take into account files that have already been copied
within sub-folders in the sketch, and not onlyafter the entire folder has
been copied.
2. Rename "Saving X As Y..." with "Saving <original_project> As
<new_project>"
3. The progress made for very large files is shown only after the ENTIRE
file has been copied. Modify processing.app.Base as well so that for large
files, the ProgressBar is updated in (almost) real time
4. Make "Done Saving" appear in Message Area only after the entire Save As
operation is complete
Ensure RGB pixels are fully opaque
Improved significantly on ProgressBar

Improvements 1,2 and 4 as mentioned in the last commit have been
implemented, i.e., ProgressBar now takes into account files within
sub-folders, the Label now reads properly in the "Save As progress" dialog
box, and "Done Saving" message appears in the message area only after the
entire process is completed.

To do:
1. Ensure progress bar reflects large files accurately
2. Add comments, minor clean-up
fixes #2341 - inconsistent bounds checks

The core datastructure IntLost, FloatList, and StringList all have
unsafe .get methods that do not perform bounds checking. This is in
contrast to their .remove methods, which do perform bounds checking.
Prior to this patch, the following would print 0:

    IntList il = new IntList();
    println(il.get(5));

But if we tried to *remove* that element, we would get an
ArrayIndexOutOfBoundException:

    il.remove(5);

This patch causes calls to .get to throw exceptions instead of returning
0 (or null in the case of StringList) for uninitialized values.
Save As Progress Bar complete, resolving issue #70

Now works for large files within folders as well.
Code is now commented as well.
Progress Bar now displays when Adding Files
Shifted ProgresSBarGUI inner class to new class

Sketch.ProgressBarGUI is now ProgressFrame
Also performed some minor formatting
All ProgressBar code shifted to ProgressFrame clss

Base is now exactly like the original.
Only change in Sketch is that a new event dispatch thread has been created
during Save As or Add File.

Base back to original
Correcting descriptions of reverse method for FloatList, IntList and StringList.
Fixes https://github.com/processing/processing-docs/issues/50
added sketchbook - tree view
removed unnecessary imports
added sketchbook shortcut
Merge pull request #2662 from ybakos/issue-docs50-reverse

Correcting descriptions of reverse method
remove %PATH% from the library path imports
fix code signing but/error on osx export (#2614)
Status Messages/Errors now clear in Contrib Manager
add copy() method to Table
return null on getString() for NaN values
add note about what was added to Table
Merge pull request #2667 from joelmoniz/clearContribMessage

Status Messages/Errors now clear in Contribution Managers