What is a Grit, and why are they called Grits?
That party is one of the several ancestors of the Liberal party. The term has lost its original content and the adjective and now simply means Liberal.
BTW, in Canada the terms "liberal" and "Liberal" have different although sometimes overlapping meanings. The Upper case L signifies the federal party or the provincial parties.
The same distinction applies to "conservative" and "Conservative".
Yanks may be more familiat with another name for Liberals, to wit, Whigs. Whigs and Tories ought to be familiar from Revolutionary War history. Canadian Liberals are still sometimes called Whigs although less so than they are called Grits. Canadian Conservatives are still called Tories.
The name stuck. The Liberals are referred to as Grits even today, although their policies have of course changed. The Conservatives are still referred to as the Tories, although the party of today is a suburban and rural middle-class party with very little "Tory" about it. The Liberals no longer support free trade; they still hate Catholics, but only in the context of hating all Christianity.
Regarding the Sheila Copps article, it is ridiculous that she thinks the socialist NDP made gains because the Liberals were "too far to the right". The NDP made gains because of the corruption issue; on some issues (like crime, for instance) they were actually to the right of the Liberals, something I don't think I have ever seen before.