make sure .eeg is binary

[sappelhoff]

(e.g., using https://github.com/bevry/istextorbinary)

[sappelhoff]

perhaps better using: https://www.npmjs.com/package/isbinaryfile

    /**
     * get_issues_IsCorrectFileType - Check vmrk, vhdr are "text" and eeg binary
     *
     * @param  {string} fPath path to the file to be tested
     * @return {(number|null)} the issue key or null, if no issue
     */
    get_issues_IsCorrectFileType: function(fPath, doNotRun){
        // if we caught earlier issues, do not even start running this.
        if (doNotRun) {return null;}
        ext = path.extname(fPath);
        const bytes = fs.readFileSync(fPath);
        const size = fs.lstatSync(fPath).size;
        var isBinary = isBinaryFileSync(bytes, size);
        // .eeg MUST be binary
        if ((ext == '.eeg') && !isBinary) {
            return 3;
        }
        // all others MUST NOT be binary
        else if (isBinary) {
            return 3;
        }
        return null;
    }