add union on range

Release/v4.2.0

Bug scenarios:
- AskSaveChanges
- AskLock
- SaveChanges
- onLocks
- onUnSaveLock

Release/v4.2.0

* 'develop' of https://github.com/ONLYOFFICE/sdkjs:
  check SectionsInfo
  Changes for classes Footnotes/Sections were added to relation map. Also was implemented merge functions for this changes.
  return scheme color for cell background

Changes for classes Footnotes/Sections were added to relation map. Also was implemented merge functions for this changes.

* 'develop' of https://github.com/ONLYOFFICE/sdkjs:
  New undo-redo scheme

* 'develop' of https://github.com/ONLYOFFICE/sdkjs: (40 commits)
  mobile scroll refactoring
  add method asc_getDataRanges to sparkline group
  delete event asc_onInitTablePictures
  fix Bug 33110
  read table custom style(if empty style content)
  Fixed bugs with merge functions for changes of classes ParaMath/Paragraph. Changes for classes ParaField and ParaRun were added to changes relation map, also implemented merge functions for changes for class ParaRun.
  Changes relation map is now common for all changes. Math changes were added to changes relation map.
  Sparkline constant was returned after last merge.
  sortDependency:delete range and undo
  Fixed bug with deleting the last row in a table.
  Implemented a merge functions for changes of classes Style/Styles.
  Implemented merge function for changes of classes ParaHyperlink/DocumentContent/Comment/Comments/ParaComment/AbstractNumbering.
  Implemented merge function for changes of classes CTable/CTableRow/CTableCell/ParaDrawing.
  For changes of ParaTextPr class were implemented function Merge.
  Fixed spelling error.
  A new scheme with merging the changes of properties. A new scheme  is the result of development of an undo in collaborative editing of a document. The changes of properties for classes Paragraph, Document, TableId now can be merged.
  For all changes added a function which returns a reverse change.
  Worked on the scheme for undo changes in fast collaboration mode.
  Classes CMathContent/CMathBase/ParaField are now inherit from a new class CChangesBaseContentChange.
  Added a new base class CChangesBaseContentChange. Content changes for classes  Document/DocumentContent/Hyperlink/Paragraph/Run/Table/TableRow now inherit from this class.
  ...

Fixed bugs with merge functions for changes of classes ParaMath/Paragraph. Changes for classes ParaField and ParaRun were added to changes relation map, also implemented merge functions for changes for class ParaRun.

Changes relation map is now common for all changes. Math changes were added to changes relation map.

Fixed bug with deleting the last row in a table.

Release/v4.2.0