add unicode superscripts and subscripts to latex substitutions
replace \\Elzxh with \\hbar to match latex usage
moved super/subscripts and hbar to manually added section
get rid of curly braces in latex super/subscripts and add \del mapping
Merge branch 'master' into sub_super
Merge pull request #6927 from lstagner/sub_super

add unicode superscripts and subscripts to latex substitutions