Organize .gitignore

Organize .gitignore by moving all patterns into a top level sorted
.gitignore file. With this change both "git status" and
"git-ls-ignore-index" should return cleanly. The later checks if any
files in the index are ignored.

graphics/text/.gitignore

@@ -1,20 +0,0 @@
-m_*.png
-wi*.png
-wilv*.png
-cwilv*.png
-data.stamp
-dmwilv*.png
-helpbg.png
-help.png
-helpoverlay.png
-helpttl.png
-prboom.png
-graphics.stamp
-textgen.mk
-credit.png
-credtext*.png
-freettl.png
-helptext*.png
-wikilrs_horiz.png
-fd?title.png
-m_*.png