tab substitution of LaTeX symbols in REPL (fixes #6340)
remove duplicate LaTeX symbols (font variations) ... fortunately, it looks like the most reasonable choice is listed first in the unicode.xml file
add \sqrt and \cbrt substitutions
add missing \mars and \female substitutions, for consistency as pointed out by @mbauman
Merge pull request #6911 from stevengj/latex

RFC: tab substitution of LaTeX symbols in REPL