edna is a work in progress text editor inspired by the UNIX standard, ed.

at the moment edna has some features, but not quite at odds with ed(1) itself.
edna has all of ed's line insertion commands

	- `a' will enter insert mode, appending lines after the current
	- `i' will enter insert mode, inserting lines before the current
	- `c' will delete the current line, and insert lines in place of the
	      deleted
(note that edna uses a single period on a line by itself to exit insert mode)

e.g.

% edna
:i
int main() {
	return 0;
}
.
:

---

among the commands are also:
	- `d' to delete the current line
	- `h' to explain the last error
	- `p' to print the current line

there is also support for multiple buffers:
	- `o' opens a delimitted list of files in new buffers
	- `b' lists the all the opened buffers
	- `next' focuses the next buffer
	- `prev' focuses the previous buffer

finally:
	- `f' to print or change the default filename
	- `w' to write the contents of the buffer
	- `e' to re-open the current file, or edit a new file
	- `q' to free the buffer and exit successfully

`q' has two variations
	- `wq' to a write and quit
	- `Q' to quit unconditionally

 if edna is given a list of files as it's arguments, they are read into memory
as buffers, and written back out on `w' and `wq' commands

edna has a ``config.h'' header file, which allows configuring a few options:
	- the `PROMPT' macro is expanded and printed before a command is read
	  from stdin. it defaults to ':', but it is fed into printf(3),
	  allowing some flexibility. the ``"%ld:", bufgetpos(buf)'' prompt is quite
	  handy, for instance
	- the `INS_PROMPT' macro is expand and printed before a line is read
	  from stdin when in insert mode.
	- the `ERROR' macro is expanded and printed when a command fails in
	  some way. following ed(1), edna defaults to the inscrutable "?\n",
	  but you may find ``"%s\n" error'' more helpful. don't forget the
	  newline!

 config.c primarily contains the arrays for commands and modes, to prevent them
from being re-defined everytime config.h is included
	- the `commands' array is indexed when a command is read from
	  stdin. it has a four fields:
		- `name', a string handle to identify the command both to the
		  user and edna
		- `func' a pointer to function to be executed,
		- `mode', a string which allows extra context to be given to
		  the function.
		- `defaddr', the default line address of the command
	- the `modes' array is indexed when a command tries the change the
	  mode, it has six fields:
		- `name', the name of the mode
		- `init', currently unused
		- `prompt', executed first
		- `input', executed second
		- `parse, executed last
	  if any of these commands return failure, the sixth member is called:
		- `error', the error handler

	at the moment, there are two modes, `command', and `insert'.

planned features:
	- regex support
	- registers
	- line marks
	- macros
	- more standard ed commands (`m',`t',`x', etc.)
	- undo trees
	- command chaining
	- plugin support