Relax Edit command ordering constraints

[rjkroege]

It wasn't obvious to me (at first) what the b edit command was actually for until I read the code. It sets the target Text instance for the subsequent sequence of sam commands inside a single exec of Edit. For example, have a convenient scratch buffer with something like this:

Edit
b <already loaded filename with more than 3 lines>
1 a/hello/
2 a/there/

So I got excited about this and thought "ah ha!", made myself a scratch buffer and wrote a bunch of sam commands to edit some code and middle clicked the whole thing. Edwood promptly crashed:

panic: Changes not in order

goroutine 23 [running]:
main.(*Elog).Insert(0xc00014e148, 0x35, 0xc000383e40, 0x3, 0x20)
	/Users/rjkroege/tools/gopkg/src/github.com/rjkroege/edwood/elog.go:151 +0x474
main.appendx(0xc00014e100, 0xc0000c0140, 0x35, 0x124ad48)
	/Users/rjkroege/tools/gopkg/src/github.com/rjkroege/edwood/ecmd.go:655 +0xdc
main.i_cmd(0xc00036a518, 0xc0000c0140, 0x7b)
	/Users/rjkroege/tools/gopkg/src/github.com/rjkroege/edwood/ecmd.go:297 +0x45
main.cmdexec(0xc00036a518, 0xc0000c0140, 0xc0000c0140)
	/Users/rjkroege/tools/gopkg/src/github.com/rjkroege/edwood/ecmd.go:109 +0x3a2
main.editthread(0xc00029f440)
	/Users/rjkroege/tools/gopkg/src/github.com/rjkroege/edwood/edit.go:153 +0xbd
created by main.editcmd
	/Users/rjkroege/tools/gopkg/src/github.com/rjkroege/edwood/edit.go:221 +0x1d5
testedwood.sh : exit status 2

While the above example would work, this slightly different example below replicates the out-of-order crash.

Edit
b <already loaded filename with more than 3 lines>
2 a/there/
1 a/hello/

So there are several distinct issues here that I'd like to fix:

• user input to Edit should never bring down Edwood
• sam would treat each of these commands as separate and apply them. If they were enclosed in { }, then sam would (silently) ignore out-of-order commands. I think Edwood should warn and ignore in that case.