Update link URL targets to minimize redirects

- Use 'https://' as default
- Bypass YouTube's link shortener to point directly to video
- Update domain name for NIH website

Author: abhro

docs/src/examples/beeler_reuter.md

@@ -20,7 +20,7 @@ In this tutorial, we first develop a CPU-only IMEX solver and then show how to m
 
 ### The Beeler-Reuter Model
 
-We have chosen the [Beeler-Reuter ventricular ionic model](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1283659/) as our example. It is a classic model first described in 1977 and is used as a base for many other ionic models. It has eight state variables, which makes it complicated enough to be interesting without obscuring the main points of the exercise. The eight state variables are: the transmembrane potential ($V$), sodium-channel activation and inactivation gates ($m$ and $h$, similar to the Hodgkin-Huxley model), with an additional slow inactivation gate ($j$), calcium-channel activation and deactivations gates ($d$ and $f$), a time-dependent inward-rectifying potassium current gate ($x_1$), and intracellular calcium concentration ($c$). There are four currents: a sodium current ($i_{Na}$), a calcium current ($i_{Ca}$), and two potassium currents, one time-dependent ($i_{x_1}$) and one background time-independent ($i_{K_1}$).
+We have chosen the [Beeler-Reuter ventricular ionic model](https://pmc.ncbi.nlm.nih.gov/articles/PMC1283659/) as our example. It is a classic model first described in 1977 and is used as a base for many other ionic models. It has eight state variables, which makes it complicated enough to be interesting without obscuring the main points of the exercise. The eight state variables are: the transmembrane potential ($V$), sodium-channel activation and inactivation gates ($m$ and $h$, similar to the Hodgkin-Huxley model), with an additional slow inactivation gate ($j$), calcium-channel activation and deactivations gates ($d$ and $f$), a time-dependent inward-rectifying potassium current gate ($x_1$), and intracellular calcium concentration ($c$). There are four currents: a sodium current ($i_{Na}$), a calcium current ($i_{Ca}$), and two potassium currents, one time-dependent ($i_{x_1}$) and one background time-independent ($i_{K_1}$).
 
 ## CPU-Only Beeler-Reuter Solver
 

docs/src/getting_started.md

@@ -1,7 +1,7 @@
 # [Getting Started with Differential Equations in Julia](@id ode_example)
 
 This tutorial will introduce you to the functionality for solving ODEs.
-Additionally, a [video tutorial](https://youtu.be/KPEqYtEd-zY) walks through
+Additionally, a [video tutorial](https://www.youtube.com/watch?v=KPEqYtEd-zY) walks through
 this material.
 
 ## Example 1 : Solving Scalar Equations

docs/src/index.md

@@ -200,7 +200,7 @@ Currently, use from R supported a subset of DifferentialEquations.jl which is do
 
 ### Video Tutorial
 
-[![Video Tutorial](https://user-images.githubusercontent.com/1814174/36342812-bdfd0606-13b8-11e8-9eff-ff219de909e5.PNG)](https://youtu.be/KPEqYtEd-zY)
+[![Video Tutorial](https://user-images.githubusercontent.com/1814174/36342812-bdfd0606-13b8-11e8-9eff-ff219de909e5.PNG)](https://www.youtube.com/watch?v=KPEqYtEd-zY)
 
 ### Tutorials
 

docs/src/tutorials/faster_ode_example.md

@@ -132,7 +132,7 @@ Since that's all setup allocations, the user-side optimization is complete.
 
 Allocations are only expensive if they are “heap allocations”. For a more
 in-depth definition of heap allocations,
-[there are many sources online](http://net-informations.com/faq/net/stack-heap.htm).
+[there are many sources online](https://net-informations.com/faq/net/stack-heap.htm).
 But a good working definition is that heap allocations are variable-sized slabs
 of memory which have to be pointed to, and this pointer indirection costs time.
 Additionally, the heap has to be managed, and the garbage controllers has to