Remove build files

These build files are not necessary.
The repository should be contains the source code only as exception of binary image files.
Files moved to root dir
Declare the methods as slots using the "public slots"

In order to enable the calling of Qt class methods from QML code, the
methods must be declared as public slots or with the Q_INVOKABLE macro.
There is no difference how you declare a slot, but if you have many slots
should better encapsulate these slots using the "public slots" declaration.
FileIO: Added isReadable method

Please call this method before opening a file to read
Byte arrays are converted implicitly to string

See: http://qt-project.org/doc/qt-5/qstring.html#QString-9
FileIO: Added isWritable method

Please call this method before opening a file to write
Added textpad application to project file
File plugin removed

However the File class is still available through JavaScript API.
FileIO class renamed
Remove unused files
Code cleanup
Convert url to local file path