[FEATURE] (master): add more .gitignore files

This is a legacy commit from before 2015-03-01.
It may be incomplete as well as inconsistent.
See COPYING.legacy and README.history for details.

src/libs/libemod/.gitignore

+# this is <.gitignore>
+# ============================================================================
+# files to be ignored by git
+# --------------------------
+# files in src/libs/libemod
+# -------------------------
+#
+# source code documentation
+*.doc
+# 
+# ----- END OF .gitignore ----- 

src/libs/libfourier/.gitignore

+# this is <.gitignore>
+# ============================================================================
+# files to be ignored by git
+# --------------------------
+# files in src/libs/libfouries
+# ----------------------------
+#
+# source code documentation
+*.doc
+# 
+# ----- END OF .gitignore ----- 

src/libs/libgrrefsub/.gitignore

+# this is <.gitignore>
+# ============================================================================
+# files to be ignored by git
+# --------------------------
+# files in src/libs/libgrrefsub
+# -----------------------------
+#
+# source code documentation
+*.doc
+# 
+# ----- END OF .gitignore ----- 

src/libs/libsff/.gitignore

+# this is <.gitignore>
+# ============================================================================
+# files to be ignored by git
+# --------------------------
+# files in src/libs/libsff
+# ------------------------
+#
+# source code documentation
+*.doc
+# 
+# ----- END OF .gitignore ----- 

src/libs/libsffu/.gitignore

+# this is <.gitignore>
+# ============================================================================
+# files to be ignored by git
+# --------------------------
+# files in src/libs/libsffu
+# -------------------------
+#
+# source code documentation
+*.doc
+# 
+# ----- END OF .gitignore ----- 

src/libs/libstfinv/.gitignore

+# this is <.gitignore>
+# ============================================================================
+# files to be ignored by git
+# --------------------------
+# files in src/libs/libstfinv
+# ---------------------------
+#
+# source code documentation
+*.doc
+# 
+# ----- END OF .gitignore ----- 

src/libs/libtf/.gitignore

+# this is <.gitignore>
+# ============================================================================
+# files to be ignored by git
+# --------------------------
+# files in src/libs/libtf
+# -----------------------
+#
+# source code documentation
+*.doc
+# 
+# ----- END OF .gitignore ----- 

src/libs/libtime/.gitignore

+# this is <.gitignore>
+# ============================================================================
+# files to be ignored by git
+# --------------------------
+# files in src/libs/libtime
+# -------------------------
+#
+# source code documentation
+*.doc
+# 
+# ----- END OF .gitignore ----- 

src/libs/libts/.gitignore

+# this is <.gitignore>
+# ============================================================================
+# files to be ignored by git
+# --------------------------
+# files in src/libs/libts
+# -----------------------
+#
+# source code documentation
+*.doc
+# 
+# ----- END OF .gitignore ----- 

src/libs/libttsynt/.gitignore

+# this is <.gitignore>
+# ============================================================================
+# files to be ignored by git
+# --------------------------
+# files in src/libs/libttsynt
+# ---------------------------
+#
+# source code documentation
+*.doc
+# 
+# ----- END OF .gitignore -----