Those Roman numeral suffixes in MM_MODEM_BAND_EUTRAN_* were replaced
with 1, 2, 3, ..., etc. This patch adds a compatibility header,
ModemManager-compat.h, to alias the old MM_MODEM_BAND_EUTRAN_* values to
the new values.
Also removed the MMSerialError implementation from `src/mm-errors.[h|c]', as it
is now included in the new `include/ModemManager-errors.h' header file. All the
other enums and errors without clashing names will be ported afterwards to the
new base code.
