Specify a temporary directory to be used instead of /tmp.

Hello,
I've experienced an issue that I didn't notice first:
When using the classic $(context-color) command for customizing my prompt like this:

PS1='[\d \A] \[\e[31m\]\u\[\e[0m\]@\[\e[0m\]$(context-color -c hostname)\h\[\e[0m\]:\w\\$ '

The prompt always used 1 line for big command lines; E.g long lines are wrapped around themselves, meaning that the new line overlaps the previous o