print different help message for frontends

First patch removes an unused class.

Second patch is to print different help messages for frontends. In current master, every frontend prints kompile's help message.

Note that this patch incomplete, help messages are not set. It would be appreciated if anyone fixes that parts or at least tell me what help messages to put there.

Current outputs:

```
➜  k git:(helpmsgs) ✗ kompile --help


usage: kompile [-addTopCell] [-c | -doc | -latex | -m | -pdf | -xml]
       [-check <arg>] [-def <arg>]  [-fastKast] [-h | -v | -version]
       [-html] [-k <arg>] [-kexp] [-l <arg>]  [-lib <arg>] [-loud]  [-ml]
       [-nofile] [-nosmt] [-o <arg>]  [-smt | -symbolic | -symeq]
       [-sortCells] [-step <arg>] [-style <arg>] [-supercool <arg>]
       [-superheat <arg>]   [-synmod <arg>] [-transition <arg>] [-unparse]
       [-w <arg>]
FIXME: kompile help msg
 -addTopCell                     add a top cell to configuration and all
                                 rules
... omitted


➜  k git:(helpmsgs) ✗ kast --help


usage: kast [-auxtabsize <arg>] [-binaryParser <arg> | -groundParser |
       -ruleParser | -sort <arg>] [--compiled-def <arg> | --k-definition
       <arg>] [-e <arg> | -pgm <arg>] [-fastKast]  [-h | -v | -version]
       [-maxwidth <arg>] [-nextline] [-nofile]  [-pretty]   [-tabsize
       <arg>]
FIXME: kast help msg
 -auxtabsize <arg>         how many spaces to indent lines which do not
                           fit into max-width
... omitted


➜  k git:(helpmsgs) ✗ kcheck --help


usage: kcheck [-def <arg> | -rlfile <arg>] [-h | -v] [-p <arg>]
       [-simplify]
FIXME: kcheck help message
 -def,--definition <arg>              main file to kompile
... omitted
```

( This will hopefully remove the confusion caused by kast's help message, see #52 )