fix/inline block mathjax and shell delimiter

[stanley2058]

This PR fixes two edge cases:

1. In editor syntax highlighting breaks after block math syntax is being written inline:
   Normal case:

   ### Title 1
   $$
   f(y) = x + 1
   $$
   #### Title 2
   

   Broken case:

   ### Title 1 // This is normal
   Test before $$ f(y) = x + 1 $$ Test after
   #### Title 2 // This is not highlighted
   

2. EOF delimiter not being correctly captured in shell/bash mode code block.

   sudo pacman -Syu
   
   cat <<EOF >> notes.txt
   This will be appended.
   $HOME will literally appear as "$HOME" because of the quotes.
   EOF
   
   pwd # this is treated as part of input to `cat`
   sudo pacman -Syu # this is treated as part of input to `cat`
   

This branch:

1. 
2. 

[Yukaii]