Small nit

Hey there, I don't really want to make a pull request here so I thought I'd just make an issue. Sorry if that's not proper etiquette! By the way, love the work.
The following lines of code appear in the source code:

``` c
erow *row = (filerow >= E.numrows) ? NULL : &E.row[filerow];
if (row) {
for (j = E.coloff; j < (E.cx+E.coloff); j++) {
if (j < row->size && row->chars[j] == TAB) cx += 7-((cx)%8);
cx++;
}
}
```

Surely this should be simplified slightly to:

``` c
if (filerow < E.numrows) {
erow *row = &E.row[filerow];
for (j = E.coloff; j < (E.cx+E.coloff); j++) {
if (j < row->size && row->chars[j] == TAB) cx += 7-((cx)%8);
cx++;
}
}
```

It seems a little off to make the conditional based off of the result of another conditional that appears literally one line above.