[dev] [surf] patches: configurable file locations, bookmark writer, history writer

I have 3 patches for surf:

config_file_locs: Makes all file and directory locations that surf
writes to into config.def.h variables. The other two patches depend on
this one.

write_bookmarks: Adds a function to append the current URI to a
(compile-time-defined) file. Default config binds it to MODKEY+B.

write_history: Modifies loadcommit to append the current URI to a
(compile-time-defined) file. A config.def.h knob can disable this.

The value of the bookmark and history files (for me anyway) is to feed
them to dmenu and load them into surf that way.

There's no locking when writing the files, so race conditions exist. I
figured I'd wait to see how this was solved for the new cookie
handling rather than doing my own thing.