The new TinyMCE in Joomla 3.5 has a serious issue.
When an editor button uses a name that is also used by TinyMCE's own buttons, it doesn't get placed at all.
For instance, a button using the title "Fun", "Form" or "Tools" will not show.
A button using the name "Container" will even cause a javascript error.

Also it isn't possible to place multiple buttons with the same title.
For instance, placing 2 buttons with the title 'My Button' will only place the first.

This PR fixes the issue, by simply prepending the name (used in javascript only) with button- and the count number of the button.
This makes the buttons unique.

Testing instructions

Test by changing the title ($button->text) of for instance the core Read More button to "Fun".
You can do that via the language overrides or directly in the php code of:
plugins/editors-xtd/readmore/readmore.php

$button->text = 'Fun';

The titles that cause issues:
AbsoluteLayout, AddOnManager, Arr, Binding, BlobCache, BookmarkManager, BoxUtils, Button, ButtonGroup, CaretBookmark, CaretCandidate, CaretContainer, CaretPosition, CaretUtils, CaretWalker, Checkbox, Class, ClassList, ClientRect, Collection, Color, ColorBox, ColorButton, ColorPicker, ComboBox, Compat, Container, Control, ControlSelection, Conversions, Delay, Dimensions, DomParser, DomQuery, DOMUtils, DomUtils, DragDropOverrides, DragHelper, Editor, EditorCommands, EditorManager, EditorObservable, EditorUpload, ElementPath, ElementUtils, EnterKey, Entities, Env, EventDispatcher, EventUtils, ExtendingChar, Factory, FakeCaret, FieldSet, FilePicker, FitLayout, FlexLayout, FloatPanel, FlowLayout, FocusManager, ForceBlocks, Form, FormatControls, Formatter, FormItem, Fun, GridLayout, I18n, Iframe, ImageScanner, JSON, JSONP, JSONRequest, KeyboardNavigation, Label, Layout, LegacyInput, LineUtils, LineWalker, ListBox, LocalStorage, Menu, MenuBar, MenuButton, MenuItem, MessageBox, Mode, Movable, Node, NodeChange, NodePath, NodeType, Notification, NotificationManager, Observable, ObservableObject, Panel, PanelButton, Path, Preview, Progress, Promise, Quirks, Radio, Range, RangeUtils, Rect, ReflowQueue, Resizable, ResizeHandle, SaxParser, Schema, ScriptLoader, Scrollable, SelectBox, Selection, SelectionOverrides, Selector, Serializer, Serializer, Shortcuts, Sizzle, Slider, Spacer, SplitButton, StackLayout, Styles, StyleSheetLoader, TabPanel, TextBox, Throbber, Toolbar, Tools, Tooltip, TreeWalker, TridentSelection, UndoManager, Uploader, URI, VK, Widget, Window, WindowManager, Writer, XHR, Zwsp