Drop doc/main.txt

This is no longer needed since we don't use the internal online help
system anymore.

Signed-off-by: Lukas Fleischer <calcurse@cryptocrack.de>

po/doc/main.pot

@@ -1,48 +0,0 @@
-#. extracted from main.txt
-msgid ""
-msgstr ""
-"Project-Id-Version: PACKAGE VERSION\n"
-"Report-Msgid-Bugs-To: \n"
-"POT-Creation-Date: 2013-07-23 10:28+0200\n"
-"PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n"
-"Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
-"Language-Team: LANGUAGE <LL@li.org>\n"
-"MIME-Version: 1.0\n"
-"Content-Type: text/plain; charset=UTF-8\n"
-"Content-Transfer-Encoding: 8bit\n"
-"X-Generator: Translate Toolkit 1.10.0\n"
-
-#: main.txt:1
-msgid ""
-"       Welcome to Calcurse. This is the main help screen.\n"
-"========================================================="
-msgstr ""
-
-#: main.txt:4
-msgid ""
-"Moving around:  Press '^P' or '^N' to scroll text upward or downward\n"
-"                inside help screens, if necessary."
-msgstr ""
-
-#: main.txt:7
-msgid ""
-"    Exit help:  When finished, press 'q' to exit help and go back to\n"
-"                the main Calcurse screen."
-msgstr ""
-
-#: main.txt:10
-msgid ""
-"   Help topic:  At the bottom of this screen you can see a panel with\n"
-"                different fields, represented by a letter and a short\n"
-"                title. This panel contains all the available actions\n"
-"                you can perform when using Calcurse.\n"
-"                By pressing one of the letters appearing in this\n"
-"                panel, you will be shown a short description of the\n"
-"                corresponding action. At the top right side of the\n"
-"                description screen are indicated the user-defined key\n"
-"                bindings that lead to the action."
-msgstr ""
-
-#: main.txt:20
-msgid "      Credits:  Press '@' for credits."
-msgstr ""