Drop duplicated tabularx import

thesis/header.tex

@@ -14,7 +14,6 @@
 \usepackage{multirow}    
 \usepackage{multicol}
 \usepackage{rotating}
-\usepackage{tabularx}
 \usepackage{array}
 \usepackage{url}
 \usepackage[ngerman,pdfview=FitH,pdfstartview=FitV]{hyperref}