lowres: bug fix -  move initialization from create() to init()

lowres objects are reused, hence they should be re-initialized.

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branch : stable
Adapting lowress frame dimensions to multiples of lowress CU size.

The full res frame is required to be extended accordingly to achieve a lowres frame with dimensions in multiples of lowres CU size.

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branch : stable
lowres intra fixes

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branch : stable
RateControl : Bug fix when previous estimated frame cost is zero

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branch : stable
MinGW: build fix for common.cpp

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branch : stable