use term.GetSize

[asukaminato0721]

fix #787

now for medium length, it won't truncate file name.

Enter receive code: 4770-citizen-valid-speed
Accept '[Reaktor] Millennium Actress - Sennen Joyuu [1080p][x265][10-bit][Dual-Audio].mkv' (1.3 GB)? (Y/n) 

Receiving (<-127.0.0.1:38286)
[Reaktor] Millennium Actress - Sennen Joyuu [1080p][x265][10-bit][Dual-Audio].mkv  18% |███                 | (255 MB/1.4 GB, 74 MB/s) [3s:15s]^C⏎           

[schollz]

@asukaminato0721 this isn't working for me on Linux, i.e. a super long filename spills over:

[asukaminato0721]

now it works with long file name.

Accept '[Reaktor] Millennium Actress - Sennen Joyuu [1080p][x265][10-bit][Dual-Audio]1111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111.mkv' (1.3 GB)? (Y/n) Y

Receiving (<-127.0.0.1:58930)
[Reaktor] Millennium Actress - Sennen Joyuu [1080p][x...  11% |██                  | (169 MB/1.4 GB, 93 MB/s) [1s:13s]^C⏎     

I set max(20, width-70)

20 is the original width, -70 is to fit with the progress bar.