Problem with use of current history

[filhodanuvem]

Hi! I'm trying use this awesome tool in my project, but I found a problem with a simple usage.

1. I write something like "select * from tags [enter]", it works.
2. I type up to use the last command.
3. I try edit that command but it's impossible, aparently, I can't increase that string.

panic: runtime error: index out of range

goroutine 1 [running]:
github.com/nemith/goline.(*GoLine).InsertRune(0x1835d140, 0x20)
    /home/cloud/sources/goworkspace/src/github.com/nemith/goline/goline.go:112 +0x64
github.com/nemith/goline.(*GoLine).Line(0x1835d140, 0x0, 0x0, 0x0, 0x0, ...)
    /home/cloud/sources/goworkspace/src/github.com/nemith/goline/goline.go:196 +0x2be
main.main()
    /home/cloud/sources/goworkspace/src/github.com/cloudson/gitql/gitql.go:30 +0x12a

goroutine 2 [syscall]:

With some time, I could try fix it and send a PR, but for now, I'm just reporting this.