Fix wrong model recognition

Parser was recognizing words with `model` keyword combination, for example `` `model` `` or `Cmodel`, as model, this is a suggestion to fix the issue. this pull request would close issue #92 and #152.
@zdne as I explained before, we have some cases that the string coming as subject would be the main line (like `super model (text/plain)`) plus the description so the string would be something like `super model (text/plain)\ndescription\n` the trim function looks at the beginning and the end of the string to remove spaces and endlines but if there are some break line in the middle of the string would be missed. It's wrong to break the line by trim function or remove `\n` in the middle. if you think of why something like `super model (text/plain)\ndescription\n` comes to this function in the first place, I think that's something to do with the logic of markdown parser.