remove Jahresplan-specific files

The Teckids calendar is now available, as a stand-alone version,
from: https://edugit.org/mirabilos/teckidscal-standalone

pgflibrarycalendar.easter.def

-% Copyright © 2017
-%	Qrrbrbirlbel
-%
-% Provided that these terms and disclaimer and all copyright notices
-% are retained or reproduced in an accompanying document, permission
-% is granted to deal in this work without restriction, including un‐
-% limited rights to use, publicly perform, distribute, sell, modify,
-% merge, give away, or sublicence.
-%
-% This work is provided “AS IS” and WITHOUT WARRANTY of any kind, to
-% the utmost extent permitted by applicable law, neither express nor
-% implied; without malicious intent or gross negligence. In no event
-% may a licensor, author or contributor be held liable for indirect,
-% direct, other damage, loss, or other issues arising in any way out
-% of dealing in the work, even if advised of the possibility of such
-% damage or existence of a defect, except proven that it results out
-% of said person’s immediate fault when using the work as intended.
-
-% This is made for http://tex.stackexchange.com/a/144186/16595
-% and used the formula from https://de.wikibooks.org/w/index.php?title=Algorithmensammlung:_Kalender:_Feiertage&oldid=670965
-
-\def\pgfcalendar@Easter#1{%
- \begingroup
-   \count0=#1\relax              % Yeah 0
-   \count1=\count0%              % K 1
-   \divide\count1 100            % K 1
-   \count2=\count1               % M 3
-   \multiply\count2 3
-   \advance\count2 3
-   \divide\count2 4              % 2 holds (3 * K +3) \ 4
-   \count3=\count1
-   \multiply\count3 8
-   \advance\count3 13
-   \divide\count3 -25
-   \advance\count3\count2
-   \advance\count3 15           % M 3
-   \count2-\count2              % S 2
-   \advance\count2 2
-   \count4=\count0              % A 4
-   \divide\count4 19
-   \multiply\count4 -19
-   \advance\count4\count0       % A 4
-   \count1=\count4              % D 1 *
-   \multiply\count1 19
-   \advance\count1\count3
-   \count5\count1
-   \divide\count1 30
-   \multiply\count1 -30
-   \advance\count1\count5       % D 1 *
-   \divide\count4 11            % R 4 *
-   \advance\count4\count1
-   \divide\count4 29            % R 4 *
-   \advance\count1-\count4      % OG 1 **
-   \advance\count1 21           % OG 1 **
-   \count3\count0               % SZ 3 *
-   \divide\count3 4
-   \advance\count3\count0
-   \advance\count3\count2
-   \count4-\count3
-   \divide\count3 7
-   \multiply\count3 7
-   \advance\count3\count4
-   \advance\count3 7           % SZ 3 *
-   \count4-\count3             % OE 4 **
-   \advance\count4\count1
-   \count3-\count4
-   \divide\count4 7
-   \multiply\count4 7
-   \advance\count4\count3
-   \advance\count4 7           % OE 4 **
-   \advance\count4\count1
-   \pgfcalendardatetojulian{\the\count0-03-\the\count4}\pgfutil@tempcnta
-   \expandafter\xdef\csname pgfcalendar@Easter@\the\count0\endcsname
-     {\the\pgfutil@tempcnta}%
- \endgroup}
-\pgfqkeys{/pgf/calendar/Easter}{
-  .default=0,
-  .code={%
-      \expandafter\ifx\csname pgfcalendar@Easter@\pgfcalendarifdateyear\endcsname\relax
-        \pgfcalendar@Easter{\pgfcalendarifdateyear}%
-      \fi
-      \expandafter\pgfutil@tempcnta
-        \csname pgfcalendar@Easter@\pgfcalendarifdateyear\endcsname
-      \advance\pgfutil@tempcnta#1\relax
-      \ifnum\pgfcalendarifdatejulian=\pgfutil@tempcnta
-        \pgfcalendarmatchestrue
-      \fi}}