[New] New Text property in RtfTreeNode class.
[New] New RawText property in RtfTreeNode class.
[New] New NextNode/PreviousNode properties in RtfTreeNode class.
[New] New SelectXXXGroup(...) methods.

New SelectXXXGroup(keyword, ignoreSpecial) to find group nodes ignoring
'\*' control words.
[New] New Placeholders property in RtfMerger.

New Placeholders property in RtfMerger. It returns a Dictionary<string,
RtfTree>.
RtfMerger updates

[Upd] RtfMerger.MergeRtfDoc() method renamed to Merge().
[Upd] RtfMerger.Merge() doesn't save documents by default. It now
returns an RtfTree object.
[New] New class RtfPullParser
.gitattributes update
[Fix] Fixed special characters conversion

Wrong conversion of special characters in RtfTreeNode Text/RawText
property.
Fix #5
[Fix] Fixed RtfTreeNode.CloneNode() method

- Now CloneNode() always clone children.
- Parent, Tree and Root properties = null.
[New] RtfDocument updates

- Now it works with in-memory documents
- New properties: Text, Rtf, Tree
[Fix] \line text conversion fixed
ImageNodeTest updated
Delete tests output files
Tests output files added to .gitignore
[Fix] TAB/CR chars not properly escaped

RtfDocument.InsertText() method update to convert \t and \n chars to
\tab and \line keywords.
Fix #1
[New] Basic Unicode support

Conversion of \uN keyword to text.
Fix #6
[New] RtfMerger supports In-Memory docs

- New constructor without params.
- New Template property.
- New AddPlaceholder(string, RtfTree) method.
- RemoveLastPar option moved to Merge() method.
Fix #10
[New] RtfDocument.AddText() basic unicode support

Add unicode text using RtfDocument.AddText() method.
RtfPullParser source doc