ffmemless: fix ffm_get_int_value return value on NULL

In case the given key is not found in props , default to min
value instead of 0 as there is no guarantee that 0 is on
the valid range of values.

Signed-off-by: Kalle Jokiniemi <kalle.jokiniemi@jollamobile.com>
ffmemless: Add debug for ffm_get_int_value

Added a debug trace for ffm_get_int_value to more easily
detect oddities in parameters.

Signed-off-by: Kalle Jokiniemi <kalle.jokiniemi@jollamobile.com>
ffmemless: Add effect repeat support

Added effect repeat support to ffmemless plugin. The plugin detects if
sound.repeat is TRUE and plays the effect INT32MAX times (effectively
infinitely for user). There is also new settings parameter
"_REPEAT" to create single shot effects that consist of multiple
vibrations.

This patch fixes also a issue with the plugin not reporting
the end of playback on single shot effects.

Signed-off-by: Kalle Jokiniemi <kalle.jokiniemi@jollamobile.com>
ffmemless: Add specific effect for SMS

Added new effect for SMS that utilizes the REPEAT functionality.

Signed-off-by: Kalle Jokiniemi <kalle.jokiniemi@jollamobile.com>
ffmemless: Document system settings file usage

Added comments to ffmemless ini about the system level settings
file usage.

Signed-off-by: Kalle Jokiniemi <kalle.jokiniemi@jollamobile.com>
ffmemless: Tune STRONG, BATTERYLOW and CLOCK effect parametes

Tuned the effect parameters a bit to make them nicer. Made
battery_low use also the lately added repeat functionality.

Signed-off-by: Kalle Jokiniemi <kalle.jokiniemi@jollamobile.com>