Add feature to ask what to do when closing unsaved document.
On branch master, changes to be committed:
	modified:   src/editortabbar.cpp
	modified:   src/editortabbar.h
	modified:   src/mainwindow.cpp
	modified:   src/mainwindow.h
	modified:   src/mainwindow.ui
Fix bug which causes faults when closing tabs.
On branch master, changes to be committed:
	modified:   src/editortabbar.cpp
	modified:   src/editortabbar.h
	modified:   src/mainwindow.cpp
	modified:   src/mainwindow.h
	modified:   src/mainwindow.ui
Replace QPlainTextEdit and QSyntaxHighlighter classes with QScintilla
library.
Update documentation.
On branch master, changes to be committed:
	modified:   mycomments.txt
	modified:   src/Lepton.pro
	modified:   src/editor.cpp
	modified:   src/editortabbar.cpp
	modified:   src/editortabbar.h
	modified:   src/mainwindow.cpp
	modified:   src/mainwindow.h
	new file:   src/scintillaeditor.cpp
	new file:   src/scintillaeditor.h

Note: language selector does not work yet with new QScintilla class.
Create custom highlighting class using QScintilla. Implement
highlighting feature (not language recognition/detection).
On branch master, changes to be committed:
	modified:   src/Lepton.pro
	new file:   src/leptonlexer.cpp
	new file:   src/leptonlexer.h
	modified:   src/scintillaeditor.cpp
	modified:   src/scintillaeditor.h
Add feature to parse language files and generate language rules.  Make some previously public methods private in LeptonLexer class.
Make minor edits to some documentation and language files.
On branch master, changes to be committed:
	modified:   languages/cplusplus.xml
	modified:   mycomments.txt
	modified:   src/leptonlexer.cpp
	modified:   src/leptonlexer.h
Implement new syntax highlighting engine based on QsciLexerCustom class.
On branch master, changes to be committed:
	modified:   languages/c.xml
	modified:   src/leptonlexer.cpp
	modified:   src/leptonlexer.h
Add language selector menu.  Fix a few bugs in highlighting.
On branch master, changes to be committed:
	modified:   src/leptonlexer.cpp
	modified:   src/leptonlexer.h
	modified:   src/mainwindow.cpp
	modified:   src/mainwindow.h
	modified:   src/mainwindow.ui
	modified:   src/scintillaeditor.cpp
	modified:   src/scintillaeditor.h
Add GeneralConfig class to centralize configuration settings.  Cleanup code a little.
On branch master, changes to be committed:
	modified:   src/Lepton.pro
	modified:   src/editortabbar.cpp
	modified:   src/editortabbar.h
	new file:   src/generalconfig.cpp
	new file:   src/generalconfig.h
	modified:   src/leptonlexer.cpp
	modified:   src/scintillaeditor.cpp
	modified:   src/scintillaeditor.h
Add feature to get data from config file.
On branch master, changes to be committed:
	new file:   config/theme.conf
	modified:   src/generalconfig.cpp
	modified:   src/generalconfig.h
	modified:   src/leptonlexer.cpp
	modified:   src/scintillaeditor.cpp