changed matrix in place to use mat4x4_row extraction and vec4_inner product
fixed some embarrassing syntax and semantic mistakes
fixed bug in perspective introduced by contribution made by learnopengles
minor stylistic changes, TODO comments added
linmath.h uses radians for everything -- adjusted contributed perspective function
Fix bug with invert matrix (was copying one float instead of all floats).
Fix another instance of sizeof ptr instead of array.
Fix bug with mat4x4_translate_in_place introduced in 34cd9df850faf0bf6b9182b3500406351ad68ae0