Set tabbed layout as default for i3 on N900 (!91)

For i3 on the N900, which seems to be the only device using i3 at the
moment, I thought using Tabbed workspace layout as the default would be
best, since the screen is quite small, and having two split windows can
quickly make it impractical.

With this commit, all new windows will be created in tabbed
configuration. It is still possible to switch to stacking or standard
layout as needed, using the appropriate shortcut keys.

device/device-nokia-n900/APKBUILD

 pkgname=device-nokia-n900
-pkgver=3
+pkgver=4
 pkgrel=0
 pkgdesc="Nokia N900"
 url="https://postmarketos.org"
@@ -129,7 +129,7 @@ e023df91295fe7e410e163747d17e5b92fe3c022ff076e286778b8334368f885603b8fda65671e4a
 7f48d1a044f8c02f7b1d11487ec1f83978d9b0ea12529156e7418f82be556d9baee32b70c4d911174e388bb4941dc19519e93e7551d00ffcd825c848665ff096  weston.ini
 4e7abd1ac6223494b2ce96f7fb2dfe6116ee8a526440df07307994ed577f1860222548f7512273b5a21febac8119794774658f60e5d6976747ddc60323d26a62  bq27200_status.sh
 16c31bf28b9dcc256821b153de199bd27decc76e4bde63130c1d1556a63cf2cafb64c4d4df42e00690564fce801c5216e8e97e4262a546440fd4bc2e14eaae1c  conky.conf
-70968c0d7095d1ad935266305270c1c697bbbea451b817b22edd7e02d3218056a0163eaf9984c96df4d78b65377e0f24433cee12a76684a419806a90faf4ca4c  i3wm.conf
+653be548d48729a725fa19f8b6aa4dca87a6cf3ec877cda0f74b4dc6799e112a742675a48fac67ec90ca43639d49890abf0518a6ca01bff2aaaffeffe5bd0f52  i3wm.conf
 3bed8554400d6bbebf7e61b14f347a0f3e24b29be296c56fc829ed655cf67fa547c09bb715589b716d6c3f04492e9f3a12473dce6c7151bc15562b9d102bac2f  i3status.conf
 0b80af9fd1f36e6bc06bdfdf48352897234ac7457210649016665da8570a5a64b8a0841b4fbeb64fd7054a5246a64718cf4412f8a53024ce39b28a80984972d8  protip_shell.sh
 a91f98daa60efa2beb2ff6b405097f92edca5f1bbb9e7675499139be52ca2570712f8f06f9032ef29f636f99c8f8da8b992f746eab6424aac04260c16158bcc2  xorg.conf"

device/device-nokia-n900/i3wm/i3wm.conf

@@ -2,6 +2,8 @@ font pango:monospace 8
 
 new_window 1pixel
 
+workspace_layout tabbed
+
 mode "workspace" {
         bindsym a workspace 1
         bindsym s workspace 2