Implemented separate Cubic, Linear and Shannon interpolation algorithms.

git-svn-id: https://svn.code.sf.net/p/soundtouch/code/trunk@178 f3a24b6a-cf45-0410-b55a-8c22e2698227
Enabled keyword extension

git-svn-id: https://svn.code.sf.net/p/soundtouch/code/trunk@179 f3a24b6a-cf45-0410-b55a-8c22e2698227
Implemented integer version of linear interpolator

git-svn-id: https://svn.code.sf.net/p/soundtouch/code/trunk@180 f3a24b6a-cf45-0410-b55a-8c22e2698227
Increased Antialias filter length from 32 to 64

git-svn-id: https://svn.code.sf.net/p/soundtouch/code/trunk@181 f3a24b6a-cf45-0410-b55a-8c22e2698227
Fixed integer overflow bug in integer versions of cross-correlation routines.

git-svn-id: https://svn.code.sf.net/p/soundtouch/code/trunk@182 f3a24b6a-cf45-0410-b55a-8c22e2698227