Add TeX precompiled preamble and xypic

A precompiled header(`latex -ini`) compiled creates a `.fmt` file.
To speed up xypic's drawing, precompiled matrices are created with the `\CompileMatrices` entry in the preamble. This creates `*.xyc` files.

Author: dopefishh

TeX.gitignore

@@ -6,6 +6,7 @@
 *.fls
 *.out
 *.toc
+*.fmt
 
 ## Intermediate documents:
 *.dvi
@@ -143,6 +144,9 @@ pythontex-files-*/
 # xindy
 *.xdy
 
+# xypic precompiled matrices
+*.xyc
+
 # WinEdt
 *.bak
 *.sav