* Add classes for application and project
* Removed all globals from Fluid.h
* Extracting args and project history into their own classes
* Moving globals into Application class
* Initialize values inside headers for some classes.
* Undo functionality wrapped in a class inside Project.
* File reader and writer are now linked to a project.
* Avoid global project access
* Nodes (former Types) will be managed by a new Tree class.
* Removed static members (hidden globals) form Node/Fl_Type.
* Adding Tree iterator.
* Use nullptr instead of 0, NULL, or 0L
* Renamed Fl_..._Type to ..._Node, FL_OVERRIDE -> override
* Renaming ..._type to ...::prototype
* Splitting Widget Panel into multiple files.
* Moved callback code into widget panel file.
* Cleaning up Fluid_Image -> Image_asset
* Moving Fd_Snap_Action into new namespace fld::app::Snap_Action etc.
* Moved mergeback into proj folder.
* `enum ID` is now `enum class Type`.
The user can add an arbitrary number of highly configurable
shell commands through the setting panel. The commands can
be saved as user preferences, inside the .fl file, or exported
to an external file. Shell scripts can be limited to individual
platforms, can have shortcut keys, etc. .
* documentation will follow
* support to call `fltk-config` will follow
Change some method names to comply with FLTK style as discussed
in fltk.coredev, thread "Fl_Flex method name question".
* Rename Fl_Flex::margins(...) to Fl_Flex::margin(...)
(use singular form for all margin related methods)
* Remove Fl_Flex::setSize() and isSetSize() "backwards compatibility" methods
* Rename Fl_Flex::set_size(...) to fixed(...)
Note: the latter affects existing (pre-release) fluid (.fl) files: you may
want to edit and replace "set_size_tuples" with "fixed_size_tuples"
