Fix tooltip markdown issue

Kept me wondering why it was spewing so many warnings while hovering over this humongous task, turns out according to gtk_tree_view_set_tooltip_column docs, the value in the column has to be escaped.

Note that the signal handler sets the text with gtk_tooltip_set_markup(), so &, <, etc have to be escaped in the text.

(xfce4-taskmanager:280405): Gtk-WARNING **: 01:57:40.922: Failed to set text 'zsh -dfxc echo $$ /home/dante/.oh-my-zsh/custom/themes/powerlevel10k/gitstatus/bin/gitstatusd-linux-x86_64 --lock-fd=3 --parent-pid=46465 --num-threads=8 --max-num-staged=1 --max-num-unstaged=1 --max-num-conflicted=1 --max-num-untracked=1 --dirty-max-index-size=-1 if [[ $? != (0|10) && $? -le 128 && -z '' && -f /home/dante/.oh-my-zsh/custom/themes/powerlevel10k/gitstatus/bin/gitstatusd-linux-x86_64-static ]]; then /home/dante/.oh-my-zsh/custom/themes/powerlevel10k/gitstatus/bin/gitstatusd-linux-x86_64-static --lock-fd=3 --parent-pid=46465 --num-threads=8 --max-num-staged=1 --max-num-unstaged=1 --max-num-conflicted=1 --max-num-untracked=1 --dirty-max-index-size=-1 fi echo -nE $'bye\x1f0\x1e'' from markup due to error parsing markup: Error on line 1: Entity name “& $? -le 128 && -z '' && -f /home/dante/.oh-my-zsh/custom/themes/powerlevel10k/gitstatus/bin/gitstatusd-linux-x86_64-static ]]” is not known

Checked it with address sanitizer and the number of bytes leaked didn't increase.

Edit: I need to confirm it again

Switching "Show full command lines" off is causing a memory leak on master.