First pass at reorganizing go code into sub-packages

internal/handlers/reports/monthly_cash_flow.lua

@@ -0,0 +1,26 @@
+function generate()
+    year = date.now().year
+
+    accounts = get_accounts()
+    t = tabulation.new(12)
+    t:title(year .. " Monthly Cash Flow")
+    series = t:series("Income minus expenses")
+
+    for month=1,12 do
+        begin_date = date.new(year, month, 1)
+        end_date = date.new(year, month+1, 1)
+
+        t:label(month, tostring(begin_date))
+        cash_flow = 0
+
+        for id, acct in pairs(accounts) do
+            if acct.type == account.Expense or acct.type == account.Income then
+                balance = acct:balance(begin_date, end_date)
+                cash_flow = cash_flow - balance.amount
+            end
+        end
+        series:value(month, cash_flow)
+    end
+
+    return t
+end