Is there any good font editor?

You can try fontforge. It is available in the standard repository. Though the GUI is somewhat messy, but it's powerful and I've used it to change names of fonts.

Click the button to install:

Or with this command:

sudo apt-get install fontforge

There is another front-end to fontforge. it is mensis. Install it with

sudo apt-get install mensis

Or using this link:

If apt-get says, no such packages, use this command to refresh package database

sudo apt-get update

See this excellent FAQ in the fontforge site at sourceforge.net . And If you like reading good writings and have time to read the history of fontforge, I recommend you to read this excellent article too!

See also BirdFont. It is available in the Universe repository since Ubuntu 14.10 (Utopic Unicorn).

Install with this command :

sudo apt-get install birdfont

Newer versions can be installed from an upstream PPA :

sudo add-apt-repository ppa:birdfont-team/birdfont
sudo apt-get update
sudo apt-get install birdfont