The $Id$ keywords were used in Subversion where they can be substituted
with filename, last revision number change, last changed date, and last
user who changed it.
In Git this functionality is different and can be done with Git attribute
ident. These need to be defined manually for each file in the
.gitattributes file and are afterwards replaced with 40-character
hexadecimal blob object name which is based only on the particular file
contents.
This patch simplifies handling of $Id$ keywords by removing them since
they are not used anymore.
Added a few RCS $Id$ tags.
# Note: I have avoided changing any .h files if the corresponding .c file
# had not already been changed as I am not sure if there are any legal
# issues here. So some extensions still have PHP 3 headers.
Draft 3 of IEEE 1003.1 200x, "2.2 The Compilation Environment"
All identifiers that begin with an underscore and either an uppercase
letter or another underscore are always reserved for any use by the
implementation.