MONTREUX, Switzerland (Reuters) – Brazil's Gilberto Gil showcased joyful African-inspired music despite being tinged with themes of poverty, slavery and painful reconciliation at the Montreux Jazz Festival on Tuesday night. Teaming up with South African folk star Vusi Mahlasela also on guitar, Gil's "Viramundo" concert offered a sneak preview of an upcoming documentary on his road trip rich in cross-cultural collaboration. …