Common

• Change -- Include hittable.h from material.h; drop hit_record forward declaration (#1609)
• Change -- Refactor sphere to use ray representation for animate center (#1621)
• Change -- All headers assume implicit rtweekend.h include (#1628)
• Fix -- Big improvement to print version listing font size (#1595) and more compact line height for code listings in both print and browser.
• Fix -- Slight improvement to rotate_y::hit() function (#1484)
• Fix -- Fixed possible bogus values from random_unit_vector() due to underflow (#1606)

In One Weekend

• Fix -- Fixed usage of the term "unit cube" for a cube of diameter two (#1555, #1603)
• Fix -- Fixed broken highlighting on some code listings (#1600)

The Next Week

• Fix -- Add missing ellipsis in listing 2.62 (#1612)

The Rest of Your Life

• Fix -- Fix typo of "arbitrary" (#1589)
• Fix -- Fix X-axis label for figure 3.08 (Approximating the nonuniform f()) (#1532)
• Fix -- Corrected scatter angle theta range in section 3.5.3 (The Scattering PDF) (#1331)
• Fix -- Clarify the distinction between average and expected value (#1535)
• New -- Added a bit more explanation of Buffon's needle problem (#1529)