Add svg temporary files

The svg package creates two temporary files for each .svg file that is
included in the document (one .pdf file and one .pdf_tex file). These
are placed into a subfolder called svg-inkscape/ by default.

TeX.gitignore

@@ -185,6 +185,9 @@ _minted*
 # scrwfile
 *.wrt
 
+# svg
+svg-inkscape/
+
 # sympy
 *.sout
 *.sympy