Update sub_test to support individual tests using chpldoc.
Update sub_test to support individual tests using chpldoc.

Add new filename suffix, .doc.chpl, which indicate chpldoc should be used as compiler instead of chpl. This is similar to the .test.c suffix.

Pipe the chpldoc options all the way through each individual test, where appropriate.

CoryMcCartan/chapel,chizarlicious/chapel,hildeth/chapel,hildeth/chapel,chizarlicious/chapel,chizarlicious/chapel,CoryMcCartan/chapel,CoryMcCartan/chapel,hildeth/chapel,CoryMcCartan/chapel,hildeth/chapel,CoryMcCartan/chapel,hildeth/chapel,chizarlicious/chapel,CoryMcCartan/chapel,hildeth/chapel,chizarlicious/chapel,chizarlicious/chapel,hildeth/chapel,CoryMcCartan/chapel,chizarlicious/chapel