fix to escape text
merge
change key combined unit which for command issue

and also change some default keycombine:
    ColorSelect Ctrl + c => Ctrl + Shift + [h,i,j,k]
change dat file i/o format
Merge branch 'dat_format'
save
change Text._move_back(ref TextSpan)
made line_join(int line) private
add deleteChar unittest
add move_caret
add TextJoin and MoveCaret command
add: Text interval character manipulation
start
remove TextSpan state flg
delete interface to not yet settled tags