add encode test for iOS
remove precompiled files
Use higher level APIs for getting the number of cores if WelsCPUFeatureDetect didn't report anything

On processors without HTT, WelsCPUFeatureDetect can't return
a number of cores but might still return a nonzero set of
CPU feature flags. Previously the nonzero cpu feature flag
indicated that cpuid worked and the encoder wouldn't use the
higher level API for getting the number of cores, even though the
number of cores was left at 1.
Refactor initializing defaults in a SEncParamExt to a separate function
Add a new public method for initializing SEncParamExt to default values

This simplifies forward source compatibility when new fields are
added to SEncParamExt - when new fields are added to SEncParamExt,
this method makes sure those fields are initialized to the
default value - otherwise all API users would have to manually check
SEncParamExt every time it is updated to make sure there's no new fields
that should be set to a nonzero value by default (e.g. like
bEnableFrameSkip).
Renumber vtable entries in the C ABI test
remove boilerplate comments
make the makefile is indepent with the pch file
remove store_ref_base_pic_flag related codes in reference picture management
Merge pull request #363 from huili2/remove_store_base

remove unused codes in reference picture management
Merge pull request #362 from mstorsjo/encoder-default-params

Add a new public method for initializing SEncParamExt to default values
Merge pull request #361 from mstorsjo/get-core-count

Use higher level APIs for getting the number of cores if WelsCPUFeatureDetect didn't report anything
Merge pull request #358 from volvet/add_ios_encDemo

add encode test for iOS