delay the discovery of sensors after powerup

Calling ow_periodic() from onewire_init() only works when
DEBUG_OW_POLLING is enabled. OW_DEBUG_POLL inside ow_periodic()
delays the discovery for some time and the discovery then works.
Without DEBUG_OW_POLLING, the discovery is not being delayed and
fails for some reason.
To solve this, ow_periodic() will be first called after 50*20ms = 1s.

Signed-off-by: Maximilian Güntner <maximilian.guentner@gmail.com>
Merge pull request #213 from mguentner/1w-discovery-fix

delay the discovery of sensors after powerup
updated IRMP to rev 120
Merge branch 'master' of github.com:ethersex/ethersex
document mbr

closes #202

Signed-off-by: Maximilian Güntner <maximilian.guentner@gmail.com>
Merge pull request #221 from mguentner/mbr_docu

document mbr
added e6-style definitions for Timer/Counter3 on 1284p
added e6-style definitions for Timer/Counter3 on at90can32/64/128
fixed bit names for COM3An
fixed use of register names TCCR1A/B and MCUCSR, added e6-style definitions for Timer/Counter3 on atmega162
fix bitmask for TC1/TC3_PRESCALER_64 for at90can32/64/128
fixed bitmasks for TCn_PRESCALER_xy
fixed bitmasks for TCn_PRESCALER_xy
fixed bitmasks for TCn_PRESCALER_xy
fixed use of register names TCCR1A/B, fixed TCn_PRESCALER_xy bitmasks, added e6-style definitions for Timer/Counter3 on atmega64
fixed TCn_PRESCALER_xy bitmasks, added e6-style definitions for Timer/Counter3 on atmega128
fixed Timer/Counter3 TIMSK and TIFR bits
whitespace cleanup
removed redundant define MCU_HAS_TC3
Merge pull request #226 from michaelb42/e6_add_Timer_Counter3_support

Add Timer/Counter3 support, fix issues #223 and #225 for several controllers