add format checking in praat.py for TextGrid files

[kevanini]

Users sometimes provide a TextGrid input file to FAVE-extract that has a formatting error, such as the following (note the two newline characters after "HH:

        intervals [403]:
            xmin = 146.703
            xmax = 146.72091856991668
            text = "HH

"

praat.py crashes while trying to read in this file with the following error:

File "/home/speech/Resources/Tools/FAVE/FAVE-extract/bin/praat.py", line 540, in read
jmin = round(float(line.strip().split('=')[1].strip()), 3) # line reads "xmin = xxx.xxxxx"
IndexError: list index out of range

It would be more helpful to the user to print out the line that caused the crash so that the user doesn't need to look for it themselves after the crash. Even better would be for praat.py to check the format of the entire TextGrid file while reading it in and output information about any lines that have formatting errors.