Update code to work with Chapel 2.0, quiet some linter warnings

[DanilaFe]

This PR is best reviewed commit-by-commit.

The main goal was to fix the Chapel code in the examples that no longer works under Chapel 2.0. Some notable changes fixed by this PR:

• Tuple indexing used to be 1-based, but is now 0-based, necessitating a change to vararg function demonstration
• The dmapped keyword now requires new, and the distributions are called blockDist and cyclicDist instead of Block and Cyclic
• The isfull() method on sync variables is now isFull (a property)
• imode is now ioMode
• Using exp requires use Math
• direct atomic real >= real comparison is no longer supported, so use .read()

This PR also fixes a number of small typos and bugs (omitted variables, incorrect names (T vs temp), etc.

The most significant linter-specific change is that do is not necessary in loops with {: do is for single-statement loops, { is for loops with multiple statements.

Also, some of the output seems to expect non-25 boundary conditions, whereas it sets up with 25 boundary conditions. This PR changes the boundaries to 0 for that portion of the code, so that the output of the program matches the expected output.

[github-actions]

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[razoumov]

Thank you, Daniel! Please give me a couple of days to review this.

[razoumov]

Thank you @DanilaFe -- all looks good, after a couple of very small corrections. Merging into the main branch.