Merge lp://staging/~ipv64ever/terminator/custom_commands_plugin_complex_cmd into lp://staging/terminator/gtk3

Custom Commands Plugin: Added complex option.

This option enables parsing of special characters in command:
  \n - send new line
  \p - add 1 sec delay

This new option doesn't conflict with old Custom Command config.
By default all existing commands get this option disabled

Added unit tests of command parsing command.

At this moment Custom commands plugin allow to send only one string with ending '\n' character.

I suggest to add ability to create complex command. Each part of command is sent one by one.
For example command "command1\ncommand2\ncommand3" will be made as following:

'command1\n'
'command2\n'
'command3\n'

There's also an ability to add delays between commands using "\p" chars.
Example 'command1\n\pcommand2\n\p\pcommand3' will be made as following:

'command1\n'
1 sec delay
'command2\n'
2 sec delay
'command3\n'

Command parsing affects only on these two "\n" and "\p" characters in command

I use terminator in my work and i often have to login on embedded boards remotely through serial port.
Each time i type login, then send password using custom command, then sudo su and finally root password again. It's anoying especially when i have to do it a lot.