Minor documentation and script cleanups (#6868)

* Remove mention of no longer used IRC network

Channels exist on matrix, and on libera.chat now.

* Correctly match only files with .png extension

The current search would match files such as 'createpng'.

* Fix comparison in script

The result was always false, due to comparing a literal string instead of a variable.

* Use correct license files from upstream

Correct license files obtained from:
https://www.gnu.org/licenses/old-licenses/gpl-2.0.txt
https://www.gnu.org/licenses/gpl-3.0.txt
https://www.gnu.org/licenses/old-licenses/lgpl-2.1.txt
https://www.gnu.org/licenses/lgpl-3.0.txt

* Refresh several shell scripts

This fixes several shellcheck warnings, as well as makes the code more
robust and have consistent codestyle between all the files.

* Trim excess whitespace

1 files changed, 12 insertions, 14 deletions

diff --git a/LICENSE.GPL-3 b/LICENSE.GPL-3
index 443254047..f288702d2 100644
--- a/LICENSE.GPL-3
+++ b/LICENSE.GPL-3
@@ -1,12 +1,11 @@
+                    GNU GENERAL PUBLIC LICENSE
+                       Version 3, 29 June 2007
 
-		    GNU GENERAL PUBLIC LICENSE
-		       Version 3, 29 June 2007
-
- Copyright (C) 2007 Free Software Foundation, Inc. <http://fsf.org/>
+ Copyright (C) 2007 Free Software Foundation, Inc. <https://fsf.org/>
  Everyone is permitted to copy and distribute verbatim copies
  of this license document, but changing it is not allowed.
 
-			    Preamble
+                            Preamble
 
   The GNU General Public License is a free, copyleft license for
 software and other kinds of works.
@@ -69,7 +68,7 @@ patents cannot be used to render the program non-free.
   The precise terms and conditions for copying, distribution and
 modification follow.
 
-		       TERMS AND CONDITIONS
+                       TERMS AND CONDITIONS
 
   0. Definitions.
 
@@ -77,7 +76,7 @@ modification follow.
 
   "Copyright" also means copyright-like laws that apply to other kinds of
 works, such as semiconductor masks.
- 
+
   "The Program" refers to any copyrightable work licensed under this
 License.  Each licensee is addressed as "you".  "Licensees" and
 "recipients" may be individuals or organizations.
@@ -510,7 +509,7 @@ actual knowledge that, but for the patent license, your conveying the
 covered work in a country, or your recipient's use of the covered work
 in a country, would infringe one or more identifiable patents in that
 country that you have reason to believe are valid.
-  
+
   If, pursuant to or in connection with a single transaction or
 arrangement, you convey, or propagate by procuring conveyance of, a
 covered work, and grant a patent license to some of the parties
@@ -619,9 +618,9 @@ an absolute waiver of all civil liability in connection with the
 Program, unless a warranty or assumption of liability accompanies a
 copy of the Program in return for a fee.
 
-		     END OF TERMS AND CONDITIONS
+                     END OF TERMS AND CONDITIONS
 
-	    How to Apply These Terms to Your New Programs
+            How to Apply These Terms to Your New Programs
 
   If you develop a new program, and you want it to be of the greatest
 possible use to the public, the best way to achieve this is to make it
@@ -646,7 +645,7 @@ the "copyright" line and a pointer to where the full notice is found.
     GNU General Public License for more details.
 
     You should have received a copy of the GNU General Public License
-    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 Also add information on how to contact you by electronic and paper mail.
 
@@ -665,12 +664,11 @@ might be different; for a GUI interface, you would use an "about box".
   You should also get your employer (if you work as a programmer) or school,
 if any, to sign a "copyright disclaimer" for the program, if necessary.
 For more information on this, and how to apply and follow the GNU GPL, see
-<http://www.gnu.org/licenses/>.
+<https://www.gnu.org/licenses/>.
 
   The GNU General Public License does not permit incorporating your program
 into proprietary programs.  If your program is a subroutine library, you
 may consider it more useful to permit linking proprietary applications with
 the library.  If this is what you want to do, use the GNU Lesser General
 Public License instead of this License.  But first, please read
-<http://www.gnu.org/philosophy/why-not-lgpl.html>.
-
+<https://www.gnu.org/licenses/why-not-lgpl.html>.