Add an installation script.

This now permits simpler installation and setup of my environment,
when the core configuration is stored at `~/cshenv`.  If stored
elsewhere, the file would have to be edited.  I'll think up an automatic
solution to this later.

startup_hooks/install.sh

@@ -0,0 +1,61 @@
+#!/bin/sh
+
+# Yeah, my CSHENV Install script is written in Bourne shell.  This is because
+# CSH isn't a great scripting language, but it is a nice interactive shell.
+
+export CSHENV_LOCATION="~/cshenv"
+
+echo "Checking for ~/.login"
+if [ ! -e ~/.login ]
+then
+    echo "Installing ~/.login"
+    echo "setenv CSHENV_DIR ${CSHENV_LOCATION}" >> ~/.login
+    echo 'source ${CSHENV_DIR}/startup_hooks/login' >> ~/.login
+fi
+
+echo "Checking for ~/.tcshrc"
+if [ ! -e ~/.tcshrc ]
+then
+    echo "Installing ~/.tcshrc"
+    echo "setenv CSHENV_DIR ${CSHENV_LOCATION}" >> ~/.tcshrc
+    echo "setenv CSHENV_HIDE_SHELL_LEVEL_AT_ONE" >> ~/.tcshrc
+    echo 'source ${CSHENV_DIR}/startup_hooks/tcshrc' >> ~/.tcshrc
+fi
+
+echo "Checking for vim setup"
+if [ -e ~/.vimrc ]
+then
+    echo "Relocating vimrc"
+    mv ~/.vimrc ~/.vim/vimrc.old
+fi
+
+if [ -e ~/.vim ]
+then
+    echo "Relocating vim setup"
+    mv ~/.vim ~/.vim.old
+fi
+
+echo "Installing vim setup"
+ln -s ${CSHENV_DIR}/vim ~/.vim
+
+if [ -e ~/.gitconfig ]
+then
+    echo "Relocating git setup"
+    mv ~/.gitconfig ~/.gitconfig-old
+fi
+
+echo "Installing git configuration"
+
+echo "[include]" >> ~/.gitconfig
+echo "  path = ${CSHENV_LOCATION}/git/gitconfig" >> ~/.gitconfig
+echo "" >> ~/.gitconfig
+
+echo "[user]" >> ~/.gitconfig
+echo "  email = adam@recursive.engineer" >> ~/.gitconfig
+echo "  name = ADAM David Alan Martin" >> ~/.gitconfig
+echo "" >> ~/.gitconfig
+echo "  signingKey = \"`hostname` Git\"" >> ~/.gitconfig
+
+echo "" >> ~/.gitconfig
+echo "[commit]" >> ~/.gitconfig
+echo "  gpgSign = true" >> ~/.gitconfig