Reset colors to default on suspend.

For most terminals this also is done with 'sgr0', but on some it
appears that we need to explicitly use the 'oc' capability.  (This
is the documented behavior in terminfo.)

go.sum

@@ -6,8 +6,6 @@ github.com/mattn/go-runewidth v0.0.10 h1:CoZ3S2P7pvtP45xOtBw+/mDL2z0RKI576gSkzRR
 github.com/mattn/go-runewidth v0.0.10/go.mod h1:RAqKPSqVFrSLVXbA8x7dzmKdmGzieGRCM46jaSJTDAk=
 github.com/rivo/uniseg v0.1.0 h1:+2KBaVoUmb9XzDsrx/Ct0W/EYOSFf/nWTauy++DprtY=
 github.com/rivo/uniseg v0.1.0/go.mod h1:J6wj4VEh+S6ZtnVlnTBMWIodfgj8LQOQFoIToxlJtxc=
-golang.org/x/sys v0.0.0-20190626150813-e07cf5db2756 h1:9nuHUbU8dRnRRfj9KjWUVrJeoexdbeMjttk6Oh1rD10=
-golang.org/x/sys v0.0.0-20190626150813-e07cf5db2756/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20201119102817-f84b799fce68 h1:nxC68pudNYkKU6jWhgrqdreuFiOQWj1Fs7T3VrH4Pjw=
 golang.org/x/sys v0.0.0-20201119102817-f84b799fce68/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/term v0.0.0-20201210144234-2321bbc49cbf h1:MZ2shdL+ZM/XzY3ZGOnh4Nlpnxz5GSOhOmtHo3iPU6M=

tscreen.go

@@ -1682,6 +1682,7 @@ func (t *tScreen) disengage() {
 	ti := t.ti
 	t.cells.Resize(0, 0)
 	t.TPuts(ti.ShowCursor)
+	t.TPuts(ti.ResetFgBg)
 	t.TPuts(ti.AttrOff)
 	t.TPuts(ti.Clear)
 	t.TPuts(ti.ExitCA)