Add Subtitle struct
Add Subtitles class

This only has write function for now.
Add Subtitle and Subtitles to project

Specify c++11 standard.
Add gui bits

Add window title and icon.
Add Number column and sort by it.
Add a few menu items.
Subtitle: shorten variable names

Make text be QStringList;
Subtitles: updates

Store subtitles as vector -- not map (as some broken subtitles might not
have the number).
Rename write to save.
Add open function.
Open and save subtitles
Don't save invalid subtitles
Add accelerators to menu items
Subtitle: remove unnecessary ctors

Add pos to temporarily hold positioning data.
Subtitles: read positioning data

Although, we don't save it at the moment, as it is not evaluated.
Fill data directly into Subtitle struct, when reading.
Subtitles: properly decode utf8