Fix definition of F28 key.

Shitf modifier adds 12 to the function number of the function keys,
while Control adds 24, so Control + F4 generates F28
Fix comments in config.def.h to match field names.
Replace alignment tabs with spaces.
Prevent resizing stdin

This fixes a bug that the parent tty gets resized whenever you launch
st through command line.

The problem was that ioctl was resizing cmdfd before it gets
initialized in ttynew. Since cmdfd is a global variable, its initial
value is 0, and consequently stdin was being resized.
Update arg.h from sbase

sbase did some interesting modifications to arg.h (basically it
was fixed an incorrect use of the _ namespace), and this commit
take this last version for st.
Merge branch 'master' into workspace