Inconsistencies in directory handling

[mbollmann]

Some parts of the code make the assumption that the current directory (meaning the directory from which you start cSMTiser) is also the working directory (the working_dir given in config.yml), and break if the working directory is set to something else (which I think should be good practice...).

Two parts that I encountered:

• https://github.com/clarinsi/csmtiser/blob/master/preprocess.py#L102 creates the preprocessed LM files in the current directory, but the training script looks for them in the working directory
• https://github.com/clarinsi/csmtiser/blob/master/csmtiser/config.py#L26 assumes the paths for the training files are relative to the working directory, but paths to development and LM files are interpreted relative to the current directory

[nljubesi]

@mbollmann, thank you for reporting the issue. This is a recently introduced bug during a code reorganization process.

I now added the dev and lm paths to the process of transforming relative paths to absolute in https://github.com/clarinsi/csmtiser/blob/master/csmtiser/config.py#L28.