Convert first, *then* trim!

[SamB]

In draw_chars(), you first trim the input to the desired width and then transliterate it to the output encoding. This causes things to get out of alignment, try:

$ LANG=C ./tig 2324d6120c5de58f63b32b876bd33e99d7375dbb

to see what I mean.

[ashumkin]

742ad98

This fix breaks the case, for example, when commit message has non-ASCII characters and LC_ALL set to non-UTF-8 encoding (cp1251 in my case)

len = utf8_length(&string...)
as we can see, string is assumed to be UTF-8 string , but after encoding_iconv() it is not! And len in a result is much less then actual string length.
So, non-UTF-8 string is cut and git log looks corrupted.

P.S. And did't get what @SamB meant

try:
$ LANG=C ./tig 2324d61
to see what I mean.