Add support for more complex command prompts

[qtc-de]

The bashsession lexer did only recognize command prompts starting with
one of the characters #$%>. This commit adds support for a prefixed
block of the form [.*], which is a common layout for command prompts.

The highlighting could accidentally trigger on text starting with something like [+] $ but I guess this is okay. To make it more restrictive, one could also thing about removing the spaces between the last closing bracket and the special prompt character #$%>. If this is desired, I could change it.

Furthermore, one could also think about changing the highlighting of the command output. The current highlighting for the command output is GenericOutput, which seems to leave the output just in ordinary text color. This makes it hard to distinguish from surrounding text. Maybe it would be better to choose a dedicated highlighting for that, as it is done by GitHub:

[test@test]$ echo 'Hello World'  # echoed text appears in blue
Hello World 

However, I'm not familiar with your default styles and themes and not sure which highlighting option would be the best. If you have a suggestion, just mention it and I will add it to this PR :)

Best regards,
Tobias

[alecthomas]

Can you add a test for this please? See lexers/README for details.

[alecthomas]

The command output is highlighted by the bash lexer. eg. if you use $ echo "hello world" you will see the quoted string highlighted. Any improvements should go into that lexer.

[alecthomas]

Sorry I misread, I see you were referring to output. It's up to the theme what to do with the tokens and I think GenericOutput is pretty accurate. You should be able to override it in CSS if you wish.

[alecthomas]

Thanks!

[qtc-de]

Added test cases as requested.

Concerning the highlighting of the command output: I actually mean the output of the command, not the command itself (e.g. just the Hello World in the second line. However, I noticed that my assumption was wrong here. The GenericOutput group seems to be implemented exactly for this case. The problem was that my selected theme did not add a special color for it.

Is there any reason why certain themes do not add colors to specific syntax groups? Would it make sense to add a default color in these themes or is that not desired?