Is there a "quickload" function in Eschalon: Book I?

Sadly no, but if you're playing on Windows you can use Autohotkey. Here's an example script that binds Control+L to "quickload", assuming you're playing fullscreen 800x600:

#NoEnv
^l::
Send {Esc}
MouseMove, 500, 370
Sleep, 200
Click
MouseMove, 500, 250
Sleep, 200
Click