Remove trailing period in application summary

For the AppStream metadata (appdata.xml), there is a
rule saying that the summary shouldn’t end with a period
(as confirmed by ‘appstream-util validate-strict’).
For the .desktop file, *most* applications omit the period.

The rule is not language-dependent, so I have also
removed the period from all translations (.po files).

src/po/sat.po

@@ -318,8 +318,8 @@ msgid "Tux Paint"
 msgstr "टक्स रोङ पेरेच्"
 
 #: ../org.tuxpaint.Tuxpaint.metainfo.xml.in:9 ../tuxpaint.desktop.in:10
-msgid "A drawing program for children."
-msgstr "गिदरा़ को ला़गित् मित् गार चिता़र तेयार का़मी होरा."
+msgid "A drawing program for children"
+msgstr "गिदरा़ को ला़गित् मित् गार चिता़र तेयार का़मी होरा"
 
 #: ../org.tuxpaint.Tuxpaint.metainfo.xml.in:11
 msgid ""