New tsh

Tsh works! Version 0.2 is now available in the files section. The change log is rather long; here are the highlights:
* new module api - the new api makes eval_hooks() simpler by pushing more of the work onto the modules
* docs are being generated with doxygen
* man page: use of tsh is documented in tsh.1
* tsh looks for /etc/tshrc and ~/.tshrc at startup
* signal handling: tsh catches interrupts now

Looking forward:
The focus will shift for the immediate future to writing a module providing shell variables. Once this is functional, development of general modules for tsh can advance. I expect to make only minor changes and bug fixes to the core until the varables module is working. Documentation will continue to progress for the core.