Add explicit casts for MSVC warnings

[gillesdegottex]

Issue

Builds with MSVC compiler generate the following warnings:

tinywav.c(110,35): warning C4244: '=': conversion from 'int' to 'uint16_t', possible loss of data
tinywav.c(114,34): warning C4244: '=': conversion from 'int' to 'uint16_t', possible loss of data
tinywav.c(115,27): warning C4244: '=': conversion from 'int' to 'uint16_t', possible loss of data
tinywav.c(244,50): warning C4267: '+=': conversion from 'size_t' to 'uint32_t', possible loss of data
tinywav.c(280,50): warning C4267: '+=': conversion from 'size_t' to 'uint32_t', possible loss of data
tinywav.c(369,37): warning C4267: '+=': conversion from 'size_t' to 'uint32_t', possible loss of data
tinywav.c(406,37): warning C4267: '+=': conversion from 'size_t' to 'uint32_t', possible loss of data

Solution

This PR applies explicit type conversions, which clarify the type changes and clears the warnings.

Example

tw->h.BitsPerSample = 8 * tw->sampFmt;

becomes

tw->h.BitsPerSample = (uint16_t) (8 * tw->sampFmt);

[Sidelobe]

Fantastic, thank you!