Use buffer caches to save rendered pages and prevent unnecessary re-rendering

[Frewacom]

Most of the code for saving and restoring ncurses buffers has already been added, but they are currently not being used. The idea is that once a page has been rendered using the page tokens, we want to quickly be able to show it again without going through each token again.

The buffer cache array can store a maximum of MAX_PAGE_COLLECTION_SIZE as defined by:

TTT/src/shared.h

Line 8 in 2c833c4

#define MAX_PAGE_COLLECTION_SIZE 10

TTT/src/ui.c

Lines 11 to 27 in 2c833c4

	static void save_view_buffer() {
	assert(current_page_index >= 0);
	assert(current_page_index < MAX_PAGE_COLLECTION_SIZE);
	mvwinstr(content_win, PAGE_LINES, PAGE_COLS, page_cache[current_page_index]);
	}
	static void restore_page_buffer(int index) {
	assert(index >= 0);
	assert(index < MAX_PAGE_COLLECTION_SIZE);
	if (page_cache[index][0] == '\0') {
	return;
	}
	mvwaddstr(content_win, PAGE_LINES, PAGE_COLS, page_cache[index]);
	page_cache[index][0] = '\0';
	}