Add default mainnet/testnet URLs

Sets new default URLs, one for mainnet and one for testnet, and allows
you to specify "lokinet" (alias "lokinet") or "testnet" for the URL to
use the defaults.

lokinet-bootstrap

@@ -9,7 +9,12 @@ NC='\033[0m' # No Color
 set -e
 
 helpme=
-default_url="https://seed.lokinet.org/bootstrap.signed"
+declare -A default_url
+default_url=(
+    [lokinet]="https://seed.lokinet.org/lokinet.signed"
+    [mainnet]="https://seed.lokinet.org/lokinet.signed"
+    [testnet]="https://seed.lokinet.org/testnet.signed"
+)
 default_dest="$HOME/.lokinet/bootstrap.signed"
 
 if [ "$#" -gt 2 ]; then
@@ -18,7 +23,9 @@ fi
 
 if [ -z "$1" ]
 then
-  url="$default_url"
+  url="${default_url[mainnet]}"
+elif [ -n "${default_url[$1]}" ]; then
+  url="${default_url[$1]}"
 elif [[ "$1" = -* ]]; then
   helpme=y
 else
@@ -34,7 +41,9 @@ else
 fi
 
 if [ -n "$helpme" ]; then
-  echo "Usage: $0 [URL [DEST]] -- download bootstrap file from URL (default: $default_url) and save to DEST (default: $default_dest)."
+  echo "Usage: $0 [URL [DEST]] -- download bootstrap file from URL (default: lokinet) and save to DEST (default: $default_dest)."
+  echo "URL can be a full URL, or else 'lokinet' or 'testnet' to use the default lokinet/testnet seed URL.  'mainnet' can be used"
+  echo "as an alias for 'lokinet'."
   exit 1
 fi